Using an old router as a switch is a great way to save money and effectively expand your wired LAN. Instead of throwing it away TP-Link or ASUS of the previous generation, you can turn them into a full-fledged network switch (switch) in minutes. This solution is ideal for situations where the main router has run out of ports, and running new cables to the central point is not possible or desirable.
Unlike a regular connection, where the router creates a new subnet and assigns IP addresses, switch mode means the device becomes "transparent" to traffic. All network management remains with the main router, and the secondary device simply forwards data packets between the ports connected to it. This allows you to unite all computers, TVs, and set-top boxes into a single network. local network, providing access to shared folders and network printers without complex settings.
The conversion process requires access to the secondary device's web interface and several critical steps that must not be skipped. An error in the sequence of steps can lead to IP address conflicts or complete internet outage for connected clients. In this article, we'll cover the steps in detail, the physical connection requirements, and configuration nuances for various equipment manufacturers.
What is the difference between a router and a switch?
To understand the essence of the process, it's necessary to clearly understand the functional differences between these devices. A router is a "smart" device that manages data flows between different networks, for example, between your home LAN and the global internet. It assigns addresses via DHCP server, provides protection through NAT and a firewall. A switch operates at a lower level, simply forwarding data frames between ports based on MAC addresses, without interfering with the addressing logic.
When we configure a router as a switch, we forcibly disable its routing functions. The device ceases to be the "master" of connected devices and becomes a simple cable splitter. The key here is to disable the DHCP server and use LAN ports instead of WAN. Leaving DHCP enabled will create chaos on your network as two devices will start handing out IP addresses, resulting in unstable internet performance.
Technically, after reconfiguration, the secondary router loses its "autonomy." It no longer creates its own network. Wi-Fi (This applies to wired mode, although Wi-Fi can often be used as an access point, but that's a different topic.) All devices connected to its ports will receive IP addresses from the main router and be on the same subnet. This simplifies file sharing and network storage. NAS.
Necessary equipment and preparation
To implement this setup, you'll need at least two devices: a primary router, which is already configured and distributes internet, and a secondary router, which we'll be reconfiguring. It's important that the secondary device have at least one port. LAN (there are usually 4 pieces of yellow color) and, preferably, a port WAN (blue), although the WAN port will not be used in our diagram. A patch cord (network cable) of sufficient length is also required to connect the devices.
Before starting work, it is recommended to reset the secondary router to factory settings. This will eliminate the influence of old configurations, passwords, and possible firmware errors. To reset, press and hold the button. Reset Press and hold the key on the back of the device for 10-15 seconds until all the indicators flash. After this, the device will be accessible via the default IP address listed on the sticker on the bottom of the device.
Don't forget to prepare a computer or laptop with a network port or USB adapter. During setup, it's best to set the computer's network card to obtain an IP address automatically to avoid conflicts with static settings. It's also helpful to know the IP address of the main router (usually 192.168.0.1 or 192.168.1.1) to properly configure the static IP for the secondary device.
βοΈ Preparing for reconfiguration
Step-by-step setup of a secondary router
Configuration is performed on a computer connected directly to the secondary router. Connect the cable to any LAN port (1, 2, 3, or 4) of the secondary device and into the PC's network card. Don't touch the WAN (Internet) port for now! Open a browser and enter the router's address (e.g., 192.168.0.1). After logging into the web interface, the first thing you need to do is change the local IP address of the router itself.
Find the section Network (Network) or LAN SettingsYou need to change the device's IP address so that it is in the same subnet as the main router, but not the same. If the main router has an address 192.168.0.1, then ask the second one 192.168.0.254 or any other free address at the end of the range. This is necessary so you can access its settings again in the future without disconnecting from the main network.
The next critical step is to disable the DHCP server. Find the section DHCP Server and select the option Disable (Disable). Save the settings. After this, the router will ask you to reboot or reconnect, as its IP address has changed. Now you need to connect your computer to the main router (or simply renew the IP address) to access the internet and log into the secondary router's interface using the new address.
β οΈ Note: After changing the IP address and disabling DHCP, access to the secondary router's settings will only be possible using the new address. If you forget the address you set, you'll have to perform a hard reset using the Reset button.
What to do if you forgot your router's new IP address?
If you don't remember the static IP address you assigned to the secondary router, the only way to restore access is to perform a hard reset. Locate the reset button on the router's case, press it with a paperclip, and hold it there for 10-15 seconds while the power is on. The LEDs will blink, and the router will return to its factory settings (usually 192.168.0.1 or 192.168.1.1).
Correct physical connection (LAN-to-LAN)
After the software setup, it's time for the physical connection. Take the network cable coming from the main router (or from any free one) LAN port), and connect it in secondary routerImportant: you need to connect it to the port LAN (1-4), and NOT to the WAN (Internet) port. The WAN port on the secondary device in switch mode remains unused.
The connection diagram looks like this: Main router (LAN) β Cable β Secondary router (LAN 1)The remaining LAN ports on the secondary device (2, 3, 4) now function as ports on a regular switch. Computers, Smart TVs, and game consoles can be connected to them. All of them will receive IP addresses from the main router and have internet access.
If you connect a cable to the WAN port, the setup won't work in "single network" mode. In this case, the secondary router will attempt to create its own subnet (double NAT), which will lead to issues with port forwarding, device visibility on the local network, and potential conflicts. LAN-to-LAN mode turns the device into a "dumb" switch, which is exactly what we want.
Comparison of operating modes and configuration table
Understanding the differences between operating modes helps avoid mistakes in the future. Some modern routers (for example, Keenetic, Mikrotik) have a software mode switch where you can simply select "Reuter" or "Access Point". However, for budget models (TP-Link, Tenda, D-Link) manual configuration by disabling DHCP is a universal method.
The table below provides a comparison of the setup parameters to help you understand the process:
| Parameter | Router Mode (Default) | Switch Mode (Our Goal) | Access Point Mode (Wi-Fi) |
|---|---|---|---|
| DHCP Server | Enabled (distributes IP) | Disabled | Disabled |
| Connecting the cable | To the WAN (Internet) port | To the LAN port | To the LAN port (usually) |
| Device IP address | Any (often 192.168.0.1) | Static from the main network | Static from the main network |
| Creating a subnet | Yes (NAT) | No (transparent bridge) | No |
It's important to note that in Switch mode, Wi-Fi functions on the secondary device are typically also disabled or work incorrectly without additional settings (WDS or Client mode), as they rely on DHCP and NAT. For extended wireless coverage, it's best to use Switch mode. WDS or Repeater, if it is supported, but this is a different network topology.
Diagnostics and possible problems
After assembling the circuit, typical problems may arise. If the internet doesn't appear on connected devices, first check the IP addressing. Make sure the computer receives an address from main router (for example, in the 192.168.0.x range), not from the secondary. If the address starts with 169.254.xx, DHCP is not working or the cable is damaged.
Another common problem is IP address conflicts. If you've assigned the secondary router an address 192.168.0.1, and the main router also has the same address, the network will crash. Always change the secondary device's IP address to a unique one before connecting it to the main network. Also, check that the cable is working properly: the LAN port indicators should be lit or blinking when connected.
β οΈ Note: Interfaces and menu names may vary depending on the firmware version and manufacturer (Asus, TP-Link, Zyxel). The logic for actions (Change IP β Disable DHCP β LAN-to-LAN) remains the same for all models.
If the internet speed on the secondary router's clients is low, check the network cable's bit rate. For speeds above 100 Mbps, a Category 1 cable is required. Cat5e or Cat6, which uses all 8 wires. Cables with 4 wires will cut the speed to 100 Mbps, even if your provider's plan allows for more.
Frequently Asked Questions (FAQ)
Is it possible to use the WAN port on the secondary router in this mode?
No, in the classic router-to-switch configuration, the WAN (Internet) port is not used. The cable from the main router is connected to the LAN port. This leaves the WAN port free. Using the WAN port is only possible in "Access Point" mode on some advanced models, where this can be switched via software. However, for the universal LAN-to-LAN method, the WAN port is not required.
Will Wi-Fi work on the secondary router after this setup?
In most standard firmware versions, disabling DHCP and connecting via the LAN port can cause the Wi-Fi module to stop distributing internet or become unstable, as it's expecting router mode. For full Wi-Fi functionality, it's best to configure WDS (bridge) mode or use the "Access Point" function, if available in the menu. In pure switch mode, Wi-Fi often disables automatically.
What should I do if I can't access the secondary router's settings?
Make sure your computer is connected to it via cable and has an IP address in the same subnet (or is set to obtain an IP automatically). If you changed your router's IP address, enter the new address in your browser. If access is permanently lost, a factory reset using the Reset button will help.
Will my internet speed decrease when using my router as a switch?
With proper setup (LAN-to-LAN), there will be virtually no speed loss, as switching occurs at the hardware level. The only limitation may be port speed (for example, if the router is older and the ports are only 100 Mbps, but you have a faster data plan). Modern gigabit routers will operate at full speed.