Wiring diagram of the d link modem. Network based on xDsl modems

Useful tips

The 2500U DSL modem allows you to connect the subscriber’s computer to the Internet using telephone cable lines. It finds its application where laying the most modern high-speed communications is still difficult.

It is impossible to organize a full-fledged local network based on this 2500U router, since DSL does not have a wireless communication module. But the principles of setting up a connection between a device and the provider company are also used in more “advanced” routers.

The D-Link network device does not support many functions, without which new models are not competitive in the market.

The main ones include parameters related to absence:

built-in WiFi module for creating a local wireless network based on it;
USB connectors for connecting external drives, mobile 3G/4G wireless Internet modems;
ports for connecting to high-speed FTTx fiber optic lines.

Appearance of DSL-2500U

The delivery package for the product purchased through the retail chain includes:

ADSL modem;
splitter - a device that allows, when connected to an input telephone line, to divide the signal into a low-frequency (analog) signal for the telephone and a high-frequency (digital) signal used in the modem;
two cables with RJ-12 connectors, one of which connects the splitter and the phone, and the other connects the splitter output and the DSL modem input;
patch cord with RJ-45 connectors for connecting the router output to the input of the network card of a computer or laptop;
modem power adapter from AC mains;
operating manuals in paper form and on CD.

The rear panel of the 2500U router contains the following elements:

DSL connector for connecting the product to the “Modem” output of the splitter;
LAN connector to which network devices are connected;
5V=1A plug connector for AC adapter;
ON/OFF button (not available on all series);
Reset button to reset current settings to factory defaults.

The DSL front panel is designed to inform the user about the status of the communication lines of connected equipment and individual components of the 2500U modem. The indicators located on the front panel of the device are as follows:

Power signals whether the DSL modem's power supply is on or off.
Status informs you about the operation of the 2500U router or any errors that have occurred.
DSL shows the synchronization status of the router while working with the provider.
Internet detects the presence of a connection to the World Wide Web or the presence of critical errors in the line (red light).
LAN informs about the health of the communication line when connecting devices to the port.

Connecting 2500U and preparing for work

A telephone cable coming from the Modem connector of the splitter or directly from the ADSL telephone line connected to the apartment or house is connected to the DSL router connector. The name “Asymmetric ADSL” is sometimes heard, but is not entirely correct. Asymmetry is already inherent in the abbreviation ADSL in its first Latin letter (Asymmetric). The LAN connector of the 2500U modem is connected using a patch cord to the connector of the network card of a PC or laptop, usually built into the motherboard.

The AC adapter is the last one to be connected. Subsequent setup of the Internet connection is carried out with both devices activated. The splitter does not have a separate power supply. To operate the 2500U router, it is necessary to obtain an IP address, as well as a DNS server address automatically using the TCP/IPv4 Internet protocol.

To configure the D-Link model 2500U modem for any provider, you need to open its interface. This is done using a PC or laptop connected to the LAN port. In the address bar of the web browser you are using, opened on your computer, you must enter the value 192.168.1.1. specified in the attached operating instructions. Then press Enter on your keyboard. In the window that opens, you need to fill in the “Username” and “Password” fields.

By default, for most routers these values will be the login and password admin/admin. After this, you need to click “Login”. Next - go to the main page of the interface; for different versions of firmware the software (software) has its own appearance.

For auto-configuration, the DSL-2500U router requires clicking the “Connect Internet” tab (Quick Setup, Wizard) on the main interface page. The DSL modem is configured by the “Setup Wizard”. It requires data received by the user from the provider. Setting up the 2500U is, in fact, semi-automatic, since at various stages it is necessary to manually enter data from the contract. To go to the next step, click on the “Next” stencil.

There are many versions of the 2500U modem. From here you can see the variety of WAN interfaces. In the first step, you need to select the connection type: PPPoE, PPPoA, IPoA, IPoE, “Static IP”, “Dynamic IP”, Bridge.

If you continue to set up DSL sequentially, you will need to additionally enter the values of the VPI and VCI parameters, depending on the region of the operator providing the services.
For connections like PPPoE, PPPoA, a username and password are required, provided by the provider. They remain unchanged. They are entered only when setting up 2500U and are saved the next time the equipment is turned on.

Static IP requires entering the Internet address (paid) assigned by the provider, which remains unchanged throughout the operator’s operation area. Dynamic IP does not require any user action when setting up an Internet connection.

Connecting to the Internet manually using the example of some providers

With manual configuration, it is possible to configure the 2500U modem for the user and set all the necessary parameters, without excluding those that are required for the type of connection of each Internet operator. On the DSL modem administration page, go to the “Advanced Setup” tab.

"Home ru"

After entering the advanced settings of the 2500U router, click on the “Network” tab in the top row and enter its menu. Next, select the WAN section and click “Add”. The operator uses PPPoE-. It must be selected from the list provided.

In the “Username”, “Password” and “Password Confirmation” fields you must write down the data received from the provider and specified in the contract. You must check the Keep Alive box.

Find out the values of the VPI and VCI indicators by calling your provider. They must be entered in the appropriate fields.

This operator additionally uses a binding to the MAC address of the equipment used. This address is the physical device identifier assigned to it during manufacturing. Before you start setting up the 2500U, you must inform your provider. Address information is located on the DSL modem label located on the bottom of the case. It is a sequence of 12 numbers and Latin letters and is designated MAC ID.

If there is no address on the label, the information is available in the extended menu. To do this, click on “Device Info” in the top row of tabs. For router firmware version 1.0.50, the physical address is designated LAN MAC.

After filling in the required fields, click on “Save”. The Internet indicator on the front panel of the device should light up after saving the configuration in an average of 20-30 seconds.

In the WAN tab, select the Home section, and then click ADD (“Add”). On the connection creation page, enter the VPI data, VCI from the agreement with the regional provider Rostelecom, and in the Service Category column, select UBR Without PCR from the list. To continue, click Next.

On the next settings page, check the PPP over Ethernet box and click Next.

After this, you need to enter information about the username and password from the agreement in the PPP Username and PPP Password fields. And also check the Keep-Alive item. The last action maintains the connection in case of accidental loss of connection and its subsequent restoration. Then click Next to go to a new page.

Check the following items here: Enable NAT, Enable Firewall, Enable WAN Service. In the last paragraph about service maintenance, write Rostelecom.

After clicking Next, you will be taken to a page with summary information. After checking that it matches the previously entered values, click Finish. Now it is possible to monitor connection signaling using the Internet indicator on the front panel of the DSL modem.
We discussed the setup details in more detail in the article.

"Beeline"

This operator assumes that the user has equipment that supports an L2TP WAN connection. The technical specifications of the 2500U modem in question indicate the following types of connections:

PPPoA.
PPPoE.
IPoA.
IPoE.

A connection from the Beeline operator is not provided for the DSL router. It is supported by the manufacturer D-Link in later models, for example, DIR-300.

NetByNet

On the main page of the interface, in its menu, you can go to the connection settings by selecting the WAN tab, and in it, the Home section. The connection is created by clicking on ADD. A new page allows you to select the type of connection from the contract. The 2500U modem in question is available with a PPPoE connection when receiving a network address automatically and PPPoE with a static address received from the provider.

In both options, the subscriber agreement contains a username and password. They must be entered in the appropriate fields. The entered password must be confirmed in the appropriate field.

After this, you need to check the “Clone address” option. In this case, the provider will see the MAC address of the computer with which the DSL modem works. Always is written in the mode selection field. In this case, the connection will be stable in case of possible failures along the communication line. The entry is completed by clicking on the Next stencil.

On the new page you need to check the following boxes: Enable Firewall, Enable NAT.

In the case of a PPPoE connection with a local (static) IP address, you must additionally check the Static IP option.

In this case, after clicking Next, a page will open where you need to fill in the fields with data from the contract: the address assigned by the provider, the subnet mask, the gateway used, the preferred and alternative DNS server addresses.

The entered information is saved after pressing the Save Settings button. On the next page you need to check the data of the created connection reflected on it. If their values are correct, click the Finish stencil. After a while - no more than 20-30 seconds - the Internet indicator on the front panel of the 2500U router should light up, which will confirm the presence of a connection with the provider.

Bridge operating mode

With the listed providers, the DSL modem works only in router and transparent bridge modes. The repeater (repeater), amplifier, adapter or access point modes are not available to it.

If, with the settings set and saved, you need to use the 2500U modem in bridge mode, this will not cause any difficulties. To do this, go to the “Manually configure” tab by clicking on it with the cursor. On the page, go to the WAN section, and in it - the Home subsection. In the created connection, adjust its type: PPPoE to Bridge, leaving the other settings unchanged.

Additionally, “Encapsulation Type” and Service Category are added. For the first parameter, Bridged IP over ATM LLC SNAP is selected, and for the second, UBR is selected.

At the last step, click Finish on the stencil. After such a change, the DSL router only performs the function of transferring information from the telephone line to the computer and vice versa.

In bridge mode, the 2500U router works with only one computer in the general case. But the DSL model in question initially has only one LAN connector. The built-in firewall stops working. The computer takes over the protection against network attacks. Network Address Translation (NAT) and the printer stop working.

IPTV

For the set-top box required for interactive television, you must allocate a separate LAN port. IPTV receives a stream of information directly from the provider. On other router models, the dedicated port is programmatically switched to transparent bridge mode and can no longer be used for other purposes. The 2500U modem has only one LAN port and the consumer has to decide on priority connection. The question concerns changing settings.

IPTV requires a Bridge connection to work. It is necessary to set the values of the VPI and VCI parameters from the contract in the WAN section.

In the “Miscellaneous” settings section, check the “Enable IGMP” option. After this, the port is “given” for IPTV.

Parental control

This setting is in addition to the basic functions of the 2500U. On the administration page, click on the “Manually configure” tab. In the top menu of the tabs that open, select “Control” and click on it.

After clicking “Add”, the opportunity to create a new rule appears. The local network for the DSL modem in question consists of only one computer, so only one rule is created.

It indicates the MAC address of the PC, enters an arbitrary name and puts a check mark in the “Enabled” item. After this, a schedule is drawn up, which includes the days of the week, hours, minutes of the beginning and end of the work opportunity.

In the “URL filter” section, you can block/allow the operation of user-specified sites. Port 80 is selected. The settings are completed by clicking on “Save”.

Dynamic DNS

Configuring this parameter in DSL refers to the advanced version of routing settings. Access is made by clicking on the “Advanced” tab. Dynamic DNS (DDNS) operates in dynamic IP mode, allowing each address change - in digital form - to leave a permanent domain name.

Security settings (antivirus, firewall) on the 2500U modem

Access to security settings in the DSL modem is provided from the main menu by selecting the “Firewall” (firewall) tab. Here you create IP filtering rules for dangerous and working addresses. To create a new rule, click on the “Add” stencil. Virtual servers and DMZ zones (virtual server dmz) are also created here. They are capable of redirecting all Internet traffic to a specific IP address on the local network.

Possible malfunctions and ways to eliminate them

All problems that arise during the operation of DSL routers model 2500U are divided into the following groups:

consumer equipment software;
system hardware;
faults occurring at the service provider.

In the first case, it is necessary to separate situations when they arise at the initial stage of setup, and failures that appear during operation of the DSL modem. At the initial stage, setting up the 2500U must be carried out in strict compliance with all the requirements of the manual, the sequence of operations, and saving the entered data at each stage. After completing the DSL setup process, you need to check the resulting results.

The causes of failures that occur during operation of the 2500U are often external factors: sudden surges in supply voltage or thunderstorms. In these cases, the use of uninterruptible power supplies (UPS) with an autonomous battery will be of great help. If it is impossible to continue DSL operation, you must reset the 2500U router’s settings to factory settings. And also carry out work to restore previously entered data. Firmware updating to the latest software version will be of great help.

The DSL modem indication on the front panel will help in troubleshooting the hardware (“hardware”). The exception is when the Power LED is not lit. For this option, replacing the AC voltage adapter will be useful. It is necessary to check the serviceability of the wires and measure the voltage using a multimeter. It will be useful to examine all cable connectors for their reliable connection and check the serviceability of the communication lines of the system equipment. Sometimes the PC is to blame for the lack of Internet information. If it is possible to check this version, it can be replaced for a while.

After the verification activities have been carried out, the service consumer must call the operator’s technical support service and report the problem. If the provider's equipment operates normally, assistance from warranty or repair shops is required.

Updating DSL router firmware

You need to update the 2500U router, that is, its software version, if numerous problems accumulate. Before starting DSL firmware, you need to carefully study the stickers on the product body, determine its hardware version (H/W) or revision type. As well as the software version (S/W) at the time of release. S/W version or line type are: annex a, annex b. And the revision is A, C, D.

On the website www.dlink.ru you need to download the latest file with the bin extension from the Firmware folder and save it on your computer.

On the main page of the interface, go to the “System” tab. In it, select the “Software Update” item, and on the new page, click the “Browse” button. After finding the downloaded file, click on the “Update” button to install the new 2500U router software. Once the update process is complete, your computer will automatically restart and return to factory settings. You will have to re-configure the DSL router using the technology described above.

Resetting the 2500U router to factory settings

The DSL modem has hardware and software resets. To return the hardware settings of the 2500U router to factory values, there is a Reset button recessed into a narrow socket. It must be pressed with a thin rod and held for 10-15 seconds. After this, you need to wait for a minute for the blinking to stop. Factory settings will be restored.

To perform a soft reset on the 2500U, after logging into the administration page, click on the “Manual Configure” tab. On the new page, move the cursor over the “System” inscription in the upper right corner, click it and select “Factory settings”. By clicking on the item, start the process of restoring the original values, followed by an automatic reboot of the DSL router.

Conclusion

A review of the D-Link DSL-2500U router shows that the model is used where only ADSL telephone lines exist, through which the Internet can be transmitted at a satisfactory speed. DSL is an entry-level budget device. It is impossible to organize a local network on its basis. The principle “one modem – one computer” applies here. The operating history of the 2500U modem goes back more than 10 years. DSL has rightfully earned a “well-deserved pension.”

pros

The positive qualities of DSL include:

The 2500U has a relatively easy setup process with the ability to quickly return to the original values in case of an error;
the ability to use DSL in telephone lines with a high level of interference;
availability of a large database of components for device repair.

Minuses

Negative qualities of 2500U today are considered:

lack of a wireless communication module or USB connector;
presence of only one network port;
outdated element base, leading to frequent failures;
low speed of data exchange on the network.

D-LINK DSL-2500U belongs to the entry-level network devices. Judge for yourself: there is no wireless communication module, there is only one network port, the processor is modest, the amount of memory is small. The scope of application of this modem can be described by the phrase “one modem - one computer”. There are still many places in the periphery where a connection from Rostelecom is the only way to get broadband Internet access. The DSL-2500U was specially designed for the countries of the former CIS, so it will work perfectly even on old telephone lines, the quality of which in the provinces leaves much to be desired. From our article you will learn how to connect it, configure it and make it work effectively.

Contents and price of the D-Link 2500U modem

The device comes in a cardboard box with a branded orange and black design. Inside are:

The patch cord included is simplified (UTP4). It has only four signal lines instead of the classic eight, so older network cards may not work with such a cable. Keep this in mind if you are the owner of a computer from the early 2000s or an old laptop.

The D-Link 2500U has been in production for a good ten years, so it can still be found on sale, although the advisability of purchasing such equipment is questionable, because it costs around a thousand rubles, and for this amount you can already buy an ADSL Wi-Fi router. The price of a modem on the secondary market varies widely. A “bare” device without cables and a splitter can be found for 100 rubles. A complete set with a box and a network adapter will cost 500–800 rubles.

Appearance, purpose of indicators and technical characteristics

The modem case is made of matte black plastic with ventilation holes on top. On the front panel there are LEDs indicating operating modes, and on the rear panel there are interface connectors and a socket for connecting a network adapter.

The presence of only one LAN port indicates that this device is clearly not intended for the office

Table: purpose of indicators on the front panel of the modem

Modem specifications

Several varieties (revisions) of the DSL-2500U were released, which differ only in the type of processor and flash memory. Their characteristics are almost the same.

Table: comparison of models of different versions

Model	Audit	CPU	Flash memory size	Flash memory type	RAM capacity	Number of network ports
DSL-2500U	A1	BCM6338	2 MB	Parallel	8MB	1
DSL-2500U/BRU/C	C1	BCM6332	2 MB	Serial	8MB	1
DSL-2500U/BRU/D	D1	BCM6332	2 MB	Serial	8MB	1
DSL-2500U/BRU/D	D2	BCM6332	2 MB	Serial	8MB	1
DSL-2500U/BRU/D	D3	BCM6332	2 MB	Serial	8MB	1
DSL-2500U/BRU/D	D4	BCM6332	2 MB	Serial	8MB	1

Video: review of the D-link DSL-2500U router

Connecting the modem to client equipment

To install and configure an Internet connection using ADSL technology, you need to complete several steps:

Connecting a modem-router to a telephone line and a computer.
Configuring the computer's network interface to successfully work with the modem.
Configuring Internet connection parameters via the PPPoE protocol using the modem's web interface.

Let's look at each of these processes in more detail.

Connection diagram

The DSL-2500U connection is typical: a filter-splitter is connected to the telephone line, and a modem port labeled ADSL is connected to it. The Ethernet port connects to the computer's network card or the input of a wireless router.

The modem-router is connected to the telephone line using a splitter

Connecting a modem to a telephone line

During operation, the ADSL modem transmits and receives a broadband signal with a frequency of several megahertz, therefore the connection speed greatly depends on the quality of the telephone line. This is especially true for wiring in old houses, where it is made of low-quality single-core “noodles” - low-current telephone wire from Soviet times. If there are several telephone sockets in a house/apartment connected in parallel, the connection diagram needs to be redone. The splitter is installed at the cable entry into the apartment, and the telephone wiring is connected to it. If the phone and modem are connected in parallel, the Internet will not work.

Connecting a modem to a computer

If the location of the telephone jack does not allow you to place the modem next to the computer, you will have to buy a patch cord of the required length or crimp it yourself. Two RJ-45 standard plugs are crimped onto a piece of UTP-8 wire in accordance with the diagram.

The cable for connecting the modem-router to the computer must be crimped in accordance with the standard color distribution scheme

Preparing your computer for connection - network adapter settings

Almost any router also works as a DHCP server, that is, it distributes IP addresses to client devices. Addresses are issued from the range specified in the router settings. For this mechanism to work correctly, you must configure the network adapter to automatically obtain a TCP/IP address and DNS server address. On computers running Windows, you may encounter a situation where the network adapter is assigned a static (permanent) address. This may lead to a conflict with another device on the network that receives the address automatically. The result will be loss of access to the Wi-Fi network (and the Internet too) on both devices.

To prevent such an error from occurring, you need to check the properties of the wireless adapter and switch (if necessary) it to automatically obtain addresses.

Click on the “Start” button with the right mouse button and select “Network Connections” from the user menu.
Call the network connections section from the user menu
In the network connections window, select the desired adapter and use the right mouse button to open its properties.
The network adapter properties contain TCP/IP protocol settings
From the list of protocols, select TCP/IP and double-click to bring up its settings.
All IP address values are set in the TCP/IP protocol settings for the network adapter
Configure to automatically obtain the network address and DNS server address and click OK.
The mode for automatically obtaining addresses is set by checking the boxes in the corresponding fields of the TCP/IP properties window

Modem web interface, configuration and access protection

After the computer’s network card is configured to automatically obtain an IP address, you can access the modem’s WEB interface at 192.168.1.1. The username is admin, and the default password is blank, meaning you do not need to enter it. To protect your network from third-party interference, change your access password immediately after the initial setup of the modem.

Setting up an Internet connection

After the modem is connected to the telephone line, the computer and there is access to the web interface, it’s time to set up an Internet connection. Let's do this using the example of the largest provider working with ADSL technology - Rostelecom.

Click the Add button and in the new window that opens, specify the VPI and VCI values issued by the provider. If you forgot to provide them, you can clarify the necessary data by calling the toll-free technical support line. From the Service Category drop-down list, select the UBR Without PCR option.
On the first screen of the setup wizard, enter the VPI and VCI parameters
Connection to Rostelecom is carried out using the PPPoE protocol. Select it from the list of protocols.
Connection to the Rostelecom provider is carried out using the PPPoE protocol
From the agreement with the provider, take the login and password assigned to your account and enter them in the appropriate fields of the settings window. Enable the Keep Alive option to automatically restore the connection after a connection loss.
Enter your Internet login and password, which are specified in the agreement with the provider
On the WAN settings page, enable Firewall and NAT. Be sure to activate the Enable WAN service checkbox. If you plan to watch digital TV on your computer, check the Enable IGMP Multicast option. In the Service Name field, enter the name of the created connection and click the NEXT button.
Don't forget to enable firewall and NAT options
On the settings report page, check that the entered data is correct and click Finish. The modem-router will reboot and establish a connection with the provider, so within a few minutes you will have Internet access.
After the modem reboots, a short report about the settings will appear on the screen

Video: setting up D-Link DSL-2500U

Port forwarding

Some users need to access their local network resources from the Internet: home network folders, images from a home IP camera, remote administration using Remote Administrator or Team Viewer programs, and dozens of other necessary applications. To organize the possibility of such access, so-called port forwarding is required, when a router combines an external network port and one of the internal network ports. Setting up port forwarding is easy using the modem's web interface functions.

Setting up a modem in bridge mode

The computing capabilities of the DSL-2500U are very modest. If you are using the device in router mode, then even with just one computer connected, programs with a large number of connections (torrent client or web server) can create excessive load on your modem. The result will be interruptions in operation, or even freezing of the device. The best way to operate it is to put the DSL-2500U into bridge mode and connect an inexpensive router to it, for example, DLINK DIR-300.

Open the window with the modem setup wizard (Wizard). Uncheck the DSL Auto-connect item and enter the values VPI=0 VCI=33 in the field that opens. Click Next.
The VPI and VCI parameters must be entered based on the settings of your provider
In the next Connection Type window, select Bridging, Encapsulation Mode - LLC/SNAP Bridging, click Next.
Set the network connection type to Bridging - this will put the modem in bridge mode
In the next window, check the Enable Bridge Service checkbox.
Activate the Bridge Service option
In the next window, if necessary, you can change the modem’s IP address. If the modem will be used in conjunction with a wireless router, set the address from the range provided by the wireless router's DHCP server. The subnet mask must also match.
Enter the address to access the modem settings
The final window of the setup wizard displays summary information. If all values are correct, click the Save/Reboot button to save the settings and reboot the modem.
Check the data and save changes if everything is entered correctly

Possible problems and malfunctions with the modem: diagnostics and elimination

DLINK DSL-2500U is a simple and reliable equipment, but it can also experience malfunctions that prevent normal operation. This is especially noticeable when purchasing a used modem. The table below lists common problems and their causes.

Table: typical problems with the DLINK-2500U modem-router

Symptom of the problem	Cause	Remedy
The power on indicator does not light up	The power supply is faulty	Replace the power supply with a working one. Any one with a voltage of 12V and a current of 0.5A and above is suitable
The power on indicator glows orange	The modem is in emergency recovery mode	The modem firmware is damaged. Upload new firmware using the patch cord as described in the instruction manual
DSL indicator blinks constantly	The modem cannot establish a connection with the provider's equipment	Check the condition of the connecting cables between the modem, splitter and line, as well as the splitter itself. If they are ok, contact your provider's technical support.
The modem restarts every 2–3 minutes	The power supply has failed	Replace the power supply with a working one or repair the old one
The Internet connection icon does not light up, there is no network access	The login and password in the PPPoE connection settings were entered incorrectly	Using the web interface, check your account information settings and enter the correct parameters
The modem gets very hot, the network access speed has dropped	Modem CPU load is too high	If it is not possible to reduce the number of connected clients, switch the modem to bridge mode and use it in conjunction with a regular router

Several years ago, when I was a client of the Rostelecom provider, I had a combination of a DSL-2500U modem and a cheap DIR-300 wireless router. Even though the modem was in bridge mode, it got very hot and, as a result, froze every few hours. Since the modem was already old and its warranty had long expired, it was decided to improve its thermal conditions by installing a cooling system. I installed a heatsink from an old motherboard on the processor chip, and cut a round hole in the upper part of the case where I installed a computer cooler. The temperature of the modem dropped noticeably, and then it worked without failures.

A fan from an old video card will help you forget about modem overheating forever

The power supply (network adapter) of the modem operates in an even more severe thermal regime than the device itself. The result is failure of the filter capacitors (capacitors) in the power circuits. If you are even a little comfortable with a soldering iron, you can repair the adapter yourself. A failed capacitor is easy to find: its housing will be swollen and deformed.

The first sign of a faulty network adapter is a swollen capacitor

Video: improving the cooling of the D-Link 2500U DSL modem

The D-LINK DSL-2500 modem-router is a time-tested, but very old solution, so if you are just connecting to the Rostelecom (or similar) network, purchasing it will not be a rational choice, because a combination of a modem plus a wireless router will cost more than purchasing an ADSL router with a wireless module. But if you live in the periphery and the state of telephone lines or the provider’s policy does not allow you to take advantage of high-speed tariff plans, the capabilities of the DSL-2500 are more than enough. After all, as wise ancestors wrote, an old horse does not spoil a furrow.

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Repair of ADSL modem DSL-2640U version C1.

Krylov P.V.

In that sample of modems,

Which I came across, about 80% of the faults were of the following type:
periodic blinking of all LEDs

periodic ADSL connection reset

periodic LAN reset
The assumption that these are bad electrolytes in the modem’s power supply was, in principle, confirmed. So, let's open the modem. We tear off the four rubber bands from the bottom and unscrew the screws.

General view of the modem board in the following photo

The following photo shows capacitors that you should pay special attention to. They are outlined with white lines. These are 2 electrolytes 2200 uF at 25 volts and one 470 uF at 16 volts. They are usually swollen, the rubber bands are squeezed out.

If you have an oscilloscope, you can look at the ripple level at the output of the secondary 3.3 volt power supply, which is where the capacitance of 470 uF at 16 V is located.

This is not a very happy picture. At a voltage of 3.3 volts, the ripple is something like 0.5 volts. We definitely change the capacitance of 470 microfarads.

The result of the work.

Conclusions.
The technology is not the worst, modems very rarely die from external influences, but they are not suitable for round-the-clock operation. It worked - turn off the modem, unplug the adapter from the socket, or better yet, unplug the ADSL line.

The DSL 2500U modem from the D-link company is another router of the DSL family, outwardly not much different from its older brother, but significantly inferior to it in terms of technical characteristics.

Router d link dsl 2500u: technical specifications

A detailed list of technical characteristics of the d link dsl 2500u router can be found in the following illustrations:

Brief review of the d link dsl 2500u router

Like most routers, on the front panel of the d link dsl 2500u router there is a number of indicators that inform the user about the following aspects of the device’s operation:

“POWER” - availability of power supply to the router;
“STATUS” - the operating status of the router and possible errors in the system (if the indicator is inactive or, conversely, is constantly on);
“LAN” - connection and activity of network devices;
“DSL” - DSL synchronization status;
“Internet” - informs about the presence of an Internet connection and possible errors (if the indicator lights up red).

There are four elements on the rear panel:

“DSL port” - for connecting the router to the telephone line;
“LAN port” - for connecting network devices;
“Reset” - button to reset the d link dsl 2500u router settings to factory settings;
“5V=1A” - connector for connecting a battery.

Installing and connecting a Rostelecom modem

The principle of installing and connecting the d link dsl 2500u router is elementary and no different from other models:

in a well-ventilated place away from heating elements, protecting the modem from direct sunlight;
connect the switched off router (dsl port) to the internet line (telephone cable or cable coming from the splitter);
to the “LAN” port;
connect the power supply and turn on the router.

Setting up an Internet connection on a d link dsl 2500u router

To gain access to the router’s web interface, use the address 192.168.1.1, which must be entered in the address bar of any Internet browser (the default login and password is “admin”).

The illustrations below correspond to the latest firmware version 1.0.50.

When you first log into the router interface, a window will appear asking you to carry out the initial settings of the router.

You can use either the “Setup Wizard” - in order to configure the d link dsl 2500u router in a semi-automatic mode and select only the basic parameters, or the “manual setup” - in order to “carefully” set all the necessary parameters.

In this article, we will consider in detail the manual configuration of the modem in order to have a more complete understanding of the network created by the router.

Setting up a d link 2500u modem using the “Setup Wizard”

The sequence of actions for automatically configuring the router is presented in the following illustrations:

Advanced settings of the d link 2500u router

To create an Internet connection manually, open the “Network” menu, the “WAN” section and click “Add”.

The “Create WAN connection” window will open in front of you: here in the “Connection type” line you need to select one of the proposed options, based on the data specified by the provider in the contract (the same applies to filling out the user name, password and atm interface).

"Bridge"

enter the value “VPI” and “VCI” - depending on the region and service provider;
check the boxes for “NAT” and “Firewall”.

"PPPoE" or "PPPoA"

Here, in addition to the parameters described above, you should specify:

“Username” and “Password” (twice);
if desired and necessary, enable the parameters “Connection on demand”, “PPP IP extension”, “PPP debugging” or “PPPoE forwarding”.

"Static IP"

"Dynamic IP"

There is no need to specify anything for this connection type.

Once you have completed entering your data, save your settings.

Setting up IPTV

Since the d link dsl 2500u modem offers only one “LAN port,” you will have to choose what to provide Internet access for: a TV set-top box or a computer.

In the “Days of Execution”, “Start Time of Execution” and “End Time of Execution” blocks, you must set the time interval during which the prohibiting rule will be in effect.

Go to the next section “URL filter” and check the box “Enable/disable URL filter”.

You can block individual addresses or all addresses except permitted ones.

Select one of the options and click "Change".

The next window contains two lines:

“URL address” - here you need to specify the address of the site that will be blocked by the router (or, conversely, added to the allowed ones - depending on your choice).
“Port” - for the “http” protocol, port 80.

Thus, this model is not equipped with the ability to create a wireless network - this fact and rather weak technical capabilities have long sent the “2500U” to a well-deserved “retirement” and this model has been discontinued from production.

At home, I use home Internet using ADSL technology via a D-Link modem. I will say that Internet access is not reliable. I don’t know who to blame more: either the provider; or a modem with a communication line; or maybe the user is to blame :). But I always noticed that the modem gets very hot when working. The idea of disassembling it and somehow improving the cooling of very hot elements arose a long time ago, but somehow no one got around to it. And then one spring day, I took it apart.
I turned it on, disassembled, watched about twenty minutes of online video, and began to feel for hot elements. I immediately found the culprit of global warming, it is a large BGA (microcircuit).

After palpating it, my index finger burned quite badly. That is, in fact, the entire modem, together with the case, is heated only by it. On the reverse side, at the location of the microcircuit, I discovered darkening of the printed circuit board. Although I know that the operating temperature of some radio elements is quite high, and a temperature of 70-105° is normal, I felt sorry for the poor thing and everyone around her, so I decided to install a radiator on it. I found a suitable heatsink on an old computer motherboard that was glued to the chip.
Using a screwdriver, I took the radiator from its rightful owner. I decided to place it on the modem chip using hot glue. I went shopping, found hot-melt glue only in a TV workshop, and paid 150 rubles for it.
Hot-melt adhesive is a very rare thing in our small town, so I immediately developed a backup option: we glue the radiator with superglue, applying it (in small dots) to the four corners of the microcircuit, and coat the center with KPT-8 thermal paste, sold in every computer store for 30 rubles.
Here, it is important to calculate everything correctly so that the paste that spreads over the microcircuit does not mix with the superglue. Since the radiator did not fit completely into its intended place, I had to cut it off.
In my case, the placement of the entire radiator was hampered by the screen of another, large microcircuit (not heating up), and on my friend’s exactly the same modem, this screen was missing, so I glued the entire radiator to it. To glue the radiator, apply a thin layer of glue to the microcircuit, having previously degreased the surfaces.
We press the radiator to the microcircuit and move it a little from side to side so that the layer of glue becomes more uniform and thinner. After thinking, I decided to glue the remaining part of the radiator. We glue it to the screen and the fins of the main radiator, aligning them. The heat transfer may be small, but it will definitely not get worse.
I was convinced of this by the heating of a small part of it and the screen. According to the instructions, the glue takes 24 hours to dry, but if you do not move the radiator, the product can be used even earlier, because the glue is thick enough and even without drying, it holds well. We assemble the modem and know: now we are definitely not in danger of overheating. Well, of course, we note that the speed and stability of the Internet connection has increased significantly :).