How do I get my wireless access point to work with my existing router?

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Summary: Adding a wireless access point can be a little frustrating if you're behind a router and the access point is also trying to be a router.

This is the scenario: you have an existing cable, satellite, or DSL connection to the internet that is connected to a broadband router or PC providing Internet Connection Sharing that in turn connects to your ethernet local area network. You want to add a wireless access point. Sounds easy, and it is. However there is a gotcha, and the name of the gotcha is NAT - Network Address Translation.

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The short answer is to make sure the wireless access point is not also attempting to provide NAT. How you do that will vary based on the access point, so check your documentation for NAT or for providing DHCP services to wireless clients and turn that off.

NAT is a technique that lets multiple machines on one side of your router share a single internet connection, and most importantly a single internet IP address as well. The router does this by handing out local IP addresses to each machine on your local network and translating between those addresses and the "real" internet IP address when the local computers access the internet.

Many wireless access points can be also configured to act very much like a broadband router. In fact there are several combo devices that are both a broadband router and wireless access point in one package. In either case, they may also be able to provide NAT functionality between the wireless and wired networks.

If NAT is turned on at both the broadband router and the wireless access point, all wireless devices are going through two levels of NAT to access the internet. Not only is that adding unnecessary overhead, but it also introduces some real problems. NAT "protects" the "local" devices from the remote devices ... in this case, the wireless access point will "protect" the wireless machines from the rest of your local network. In effect, it'll make them inaccessible.

So as I said earlier, the solution is fairly simple. You only need one level of NAT between the internet and the rest of your LAN. Anything on your local network is safe and does not need additional NAT. Make sure that NAT or DHCP is turned OFF on the wireless access point. (To be clear, the wireless access point may still use DHCP to get an address for itself, but it should not provide DHCP functionality to wireless devices.)

Related:

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