How to Use an Old Router to Improve WiFi and Expand Coverage

What should I keep in mind if I use a router as a WiFi AP?

Nowadays it is very normal that all the rooms in our home have RJ-45 rosettes, in fact, you yourself could throw a network cable to wire at least one room that is as far as possible from the current router. WiFi repeaters are very useful for expanding wireless coverage, but unless you spend more than 100 euros on a simultaneous triple band WiFi repeater, the performance you will get will be really low. For this reason, if you have a wired room on the other side of the main router that also acts as a WiFi access point, it would be ideal if you could reuse your old router and have WiFi coverage.

The main idea is to use this old router as a second access point in our home or workplace, to be able to reach with coverage where the main router is not able to reach. To do this, we must take into account the following:

• We will not have WiFi roaming between the main router and the old one, because it is not a WiFi Mesh system with the corresponding standards to allow it.
• We will have to configure the secondary router depending on how the main router is configured.
• The network name (SSID), security type, and the WPA2 or WPA3 access password must be exactly the same on both routers. This is so that mobile devices such as smartphones, tablets or laptops connect to one network and another and “force” a roaming, although we will notice the cut in the WiFi wireless connection.
• The interconnection between the main router and the secondary one must be done via Ethernet network cable, because normally old routers do not have the WiFi repeater functionalities.

Once we know all the requirements and aspects to take into account, we are going to see what configurations we must make in the old router.

Configuration of the old router in WiFi access point mode

We must configure the old router in a very similar way to the main router, since both must be on the same subnet. It does not matter if our old router is ADSL, it is a cable modem or a neutral router, in all of them the configuration is exactly the same. Before connecting the old router to the current local network with the main router, we must perform a series of configurations.

IP and Subnet Settings

Normally all routers use the typical network 192.168.1.0, where we can access via cable or WiFi to the administration via web through the IP address 192.168.1.1. We must make sure that the main router and the old router that we are going to reuse, make use of the exact same subnet, otherwise, we will have problems with connectivity.

Another aspect that we must take into account is the administration IP address of the router, normally all routers use 192.168.1.1, and this is a problem because we cannot have the same access IP address in both routers. We must configure the routers in the following way:

• Main router: in the LAN we must have the IP 192.168.1.1 configured with a subnet mask 255.255.255.0 or also known as / 24.
• Secondary router: in the LAN we must have a different IP that is within the same subnet, and that is outside the DHCP range of the main router. That is, if the DHCP range of the main router goes from IP 192.168.1.30 to 192.168.1.254, then we can put the IP 192.168.1.2. It is very important to put an IP within the same subnet, and use the same subnet mask.

There are some cases where the main router’s DHCP server goes from IP 192.168.1.2 to 192.168.1.254, so we don’t have any IP available. In this case, we must go to the configuration of the main router and change the range of DHCP IPs so that everything works correctly.

DHCP server configuration on the old router

Once we have configured the IP address of the old router, what we must do in this old router is to disable the DHCP server. We will have a single DHCP server in the network, which will be the main router that manages the Internet connection. It is very important that in this old or secondary router we deactivate the DHCP server, otherwise, we could have problems because if we are assigned an IP of the secondary router, the gateway will be incorrectly configured, and at the local network level we will have connectivity, but not from face internet.

WiFi network configuration

The configuration of the WiFi network in the two routers must be exactly the same, except in the WiFi channels used to avoid interference with ourselves. In this case, if the main router we have it configured in the following way:

• SSID: ITIGIC_2.4GHz
• Security type: WPA2-PSK
• Password: ITIGIC-Password-Access
• Channel: 3
• SSID: ITIGIC_5GHz
• Security type: WPA2-PSK
• Password: ITIGIC-Password-Access
• Channel: 40

The secondary router must be configured exactly the same, but changing the WiFi channels so that there is no interference.

Wired network connection

Once we have configured all the previous parameters, we can connect the old router to the local network and we will have WiFi coverage without any problem. We must connect a network cable from the main router to any LAN port, or from a switch that we have at home (which, in turn, is connected to the main router on a LAN port) to any LAN port of the old router.

It doesn’t matter which port you connect it to, the most important thing is that it is connected to the LAN port, and if your router has an RJ-45 WAN port, leave it free without connecting.

What about routers that have access point mode?

In the market there are routers such as the ASUS or AVM FRITZ! Box that allow us to configure them as a WiFi access point, to do just this in the tutorial. When we configure it in access point mode, the IP address will be obtained automatically from the DHCP server of the main router, and later we can configure the WiFi wireless network as we want.

In essence, a router in AP mode does exactly the same thing that we have done manually if the router does not have this function. The router will automatically obtain an IP within the main subnet, and later we can configure the SSID, security and WPA2 key in the router, finally, we will have to connect a network cable to the LAN port of the router so that everything works well. It is possible that in AP mode, the Internet WAN port (if we are talking about a neutral router) is also enabled as a LAN, but this depends on the router manufacturer and model.

What about routers with a WiFi repeater function?

There are routers that also have the WiFi repeater function, such as the ASUS or AVM FRITZ! Box. This function does exactly the same as a normal WiFi repeater, it will take the WiFi network from the main router, and repeat it to extend the coverage. The problem is that we will lose half the bandwidth in this “jump”, because the interconnection network is done via WiFi and not via cable, therefore, it would be better to interconnect them by cable.

Of course, the best option to have full coverage in our home is to have a WiFi Mesh system, where we will have WiFi roaming and also band-steering. However, if we want to reuse our old router we can also do it and with optimal performance.

Third-party firmware on the old router

If your old router supports third-party firmware such as DD-WRT, OpenWRT or Tomato among others, you can install these advanced firmwares and configure your router directly in WiFi access point mode, obtaining the IP of the network automatically via DHCP client, and later configure the WiFi wireless network. If a certain router model with the manufacturer’s firmware does not support AP mode, it is very possible that, if you install one of these firmwares that are compatible, you will have the functionalities of a WiFi access point or WiFi repeater.

As you have seen, configuring an old (or new) router as an access point to have greater WiFi coverage wherever we are going to connect is really easy, and we can get it done in about 15 minutes.