Bridge mode is a networking term which – at its simplest - means that the routing part of a router (the NAT function) is turned off.
Since you’re reading this, you’re probably wondering whether you need to, or should, enable bridge mode on your router or mesh Wi-Fi system.
And the answer is simple: if you’re connecting a second router (or mesh Wi-Fi system, which is essentially multiple routers) to an existing one, you should enable bridge mode on at least one of those routers.
When should I use bridge mode?
- If you’re using a second router on your network
- When you’re connecting a mesh Wi-Fi system (or security router) to your network
It’s not a good idea to have two routers trying to do network address translation on the same network as it can lead to problems such as IP address conflicts and, rarely, performance issues. This is called Double NAT.
Even if your second router or mesh system uses a different IP address to your main router (let’s say the main is 192.168.0.1 and the second router is 10.1.74.0) you could still run into problems.
Why use bridge mode?
- Increase Wi-Fi coverage
- Prevent IP address conflicts and performance issues
Aside from the two-devices-trying-to-do-the-same-job problem, there are other reasons to use bridge mode.
Let’s say you’re trying to use a second router to increase Wi-Fi coverage and your two routers support wireless bridging (since no-one wants to run a network cable between their routers). This would mean you can connect both wireless and wired devices in different room to your main router and they’ll all benefit from whatever Wi-Fi standard the routers are using to communicate – likely to be faster than powerline adapters and it’s a useful way to connect wired-only devices to a far-away main router without cables.
Another reason to use bridge mode is so that devices connected to both routers can talk to each other. For example, if you have a printer or NAS drive connected to the main router via a network cable, and devices connected to the second router won’t be able to communicate with those attached to the first, preventing you from printing or accessing files, such as in the scenario shown above. Without bridge mode, the two routers are broadcasting their own separate, private Wi-Fi networks - there's no crossover.
Enabling bridge mode (as shown below) means everything is on the same network and can talk to each other.
One last reason is to ensure that any port forwarding rules work. These days it’s rare you’ll need to use port forwarding, but you probably will if you want to run a local game server or possibly even have an internet-accessible NAS drive. Assuming those devices are connected to the secondary router, they’re unlikely to work if that second router is doing its own NAT and handing out IP addresses.
What are the disadvantages of bridge mode?
- Some features might be disabled
Mesh Wi-Fi systems are the best choice for most people these days, and they do a similar job to using a second router to increase Wi-Fi coverage. When you install them, the companion app will ask what kind of setup you have currently.
It’s likely they’ll recommend you enable bridge mode, but doing so can disable a host of features. If you have a Linksys Velop mesh system, for example, bridge mode turns off most of the useful features, such as parental controls, device prioritisation, MAC address filtering and other things.
The obvious solution would be to put your main router in bridge mode instead and let the mesh Wi-Fi system do the routing. But in many cases that’s not possible since ISP-supplied routers often lack this option. BT’s Smart Hub doesn’t support it, but replacing this with a different modem may cause other problems, such as BT TV internet channels not working.
If this is the case, then your only option would be to install the secondary router right next to your existing one and connect any wired devices to that so all devices connect to that additional router instead.
It’s worth noting that not all mesh systems support bridge mode like this: Google’s Nest Wifi only works in bridge mode if you have a single Nest router. It isn’t supported if you have multiple Wifi points. Google recommends you put your modem router in bridge mode, but as mentioned, this may not be possible.