How to Turn an Old Router into a Network Switch

Why use an old router as a network switch

Most routers include a small built-in Ethernet switch: the LAN ports are connected to a switching chip that moves traffic between wired devices on the same network. If you stop the router from performing its routing jobs, those ports still work as ordinary switch ports. That makes an old router a practical way to add wired ports for a desk, media console, or smart-home hub. The difference between the two network devices is explained in network switch and router vs switch.

Turning an old router into a switch is easiest when you only need wired connectivity. You do not have to keep the Wi-Fi radios on, and you do not have to ask your Internet provider to reconfigure anything. The main router on your network keeps doing the addressing and Internet sharing; the old router simply becomes an extra set of ports.

• An old router with at least one LAN port for the uplink and another for a device.
• An Ethernet cable long enough to connect the old router to your main network.
• The power adapter and, if you do not know the admin password, a way to factory-reset the router.

What to check before you start

Before you begin, make sure the old router can actually be configured. If you do not know its admin address or password, you can usually factory reset it and then log in to the admin page. Resetting restores the default login and makes the conversion cleaner.

Check the Ethernet ports on the old router. You need at least one port to connect to your main network and at least one more port for a device. If the old router only has one LAN port, it cannot work as a useful switch by itself. In that case, a separate device may be the better answer; see how many Ethernet ports do you need and how to connect an Ethernet switch to a router.

Also decide whether you want to keep the old router's Wi-Fi on. If you only need wired ports, turn the radios off. Leaving an old Wi-Fi radio on can create interference with your main network, and older security settings may not meet current standards. The Wi-Fi Alliance says WPA3 is mandatory for Wi-Fi CERTIFIED devices; an older router may not support WPA3, so turning Wi-Fi off is often the safer choice.

How to turn the old router into a switch

The general process is the same on most routers: connect to the old router by itself, disable its DHCP server, give it an unused LAN address on your main network, and then connect it through a LAN port. You do not need to touch the WAN port.

• Start with the old router unplugged.
• Connect a computer to one of its LAN ports with an Ethernet cable, then plug the router in.
• If you do not know the current settings, perform a factory reset.
• Log in to the admin page.
• Find the DHCP server setting and disable it.
• Change the router's own LAN IP address to an unused address in the same subnet as your main router, outside the main router's DHCP range.
• Save the settings and let the router restart.
• Connect an Ethernet cable from a LAN port on your main router or existing switch to one of the LAN ports on the old router. Leave the old router's WAN port empty.
• Plug your devices into the remaining LAN ports.
• If you are not using Wi-Fi, disable the wireless radios.

DHCP and IP address details

The most important setting is DHCP. The main router should be the only device on your network handing out IP addresses. If the old router keeps DHCP enabled, you can end up with two DHCP servers, duplicate addresses, and devices that connect to the wrong gateway. The DHCP explained article covers why this matters.

After disabling DHCP, give the old router a fixed LAN IP address that is inside your main network range but outside the addresses the main router assigns. For example, if your main router uses 192.168.1.1 and assigns addresses from 192.168.1.100 to 192.168.1.200, you could set the old router to 192.168.1.2. This is not a new rule, just a way to keep the old router reachable for future changes. If you need a reminder about static assignments, read DHCP reservation vs static IP.

Use the LAN port, not the WAN port

A router has a WAN port for the connection to your modem or ONT and LAN ports for local devices. When you repurpose the router as a switch, connect the cable from your main network to a LAN port. If you connect it to the WAN port, the old router will still try to do network address translation and routing, which can create a double NAT or block communication between devices. The WAN port types article explains why the WAN port is different.

By using only LAN ports, the old router becomes a transparent layer of your network. It passes traffic between the main router and your wired devices without routing or translating it. That is exactly what a network switch does.

Switch mode vs access point mode

The steps above give you a wired switch. If you want to reuse the old router's Wi-Fi at the same time, the process is similar but you keep the radios on and set the same network name and password as your main router. That is covered in how to use an old router as an access point.

The table below shows the two common ways to reuse an old router.

Security and safety notes

If you keep the old router as a switch with Wi-Fi off, the device no longer handles security functions like the main router does. Still, make sure the old router itself is not left with a weak admin password. NIST publishes cybersecurity and privacy guidance that emphasizes basic steps like changing default passwords and keeping software current. You can also read router security basics for plain-language advice.

As with any older electronic device, inspect the power adapter and the router body before leaving it on for long periods. The U.S. Consumer Product Safety Commission provides general home safety education that covers electrical products, so turn off and unplug anything that looks damaged. An old router that overheats, smells, or makes odd noises should be retired.

If you no longer need the old router, do not just throw it away. Performing a factory reset before recycling or giving it away removes your personal settings.

What to pick for your use

Questions

Can any old router be used as a network switch?

Most routers with at least two LAN ports and an admin page can be used. You need one LAN port to connect to your main network and one or more remaining ports for devices. If the router only has a single LAN port, it cannot be a useful switch.

Do I have to disable DHCP on the old router?

Yes, unless you want to create a separate network. Disabling DHCP prevents two servers from handing out IP addresses on the same network. The main router should be the only DHCP server.

Which port do I use to connect the old router to my main router?

Use a LAN port on both devices. Do not use the WAN port on the old router. Connecting through the WAN port can cause double NAT and prevent devices from seeing each other on the local network.

Will the old router still provide Wi-Fi if I convert it to a switch?

Only if you leave the wireless radios on and configure them as an access point. If you want a pure switch, turn the radios off. Keeping them on without the right settings can create interference and a second network.

Is it safe to keep an old router running all the time?

It is generally safe if the device is in good condition and the power adapter is not damaged. Inspect for overheating, burning smells, or cracked plastic. If any of those appear, stop using it and recycle it.