Bridge Mode

Bridge Mode turns off the normal routing functions of DHCP and NAT. That's why Apple uses the term "Off (Bridge Mode)" in AirPort Utility.

Bridge Mode would usually be the best setting to use if you already have another router on the network that is providing DHCP and NAT services. Despite what many users think though, Bridge Mode does not turn off the WiFi function on the AirPort Extreme.

Try running the AirPort Extreme in a Router Mode of DHCP and NAT.

You will see a message to the effect that you have a Double NAT on the network, and the amber light will blink slowly.

Don't worry about that for now, and check to see if all of your devices will connect to the AirPort Extreme OK. You may need to restart the modem and the AirPort Extreme to get a good Internet connection.

If everything appears to be OK, AirPort Utility provides you with an option to ignore the Double NAT notice, so the Extreme will display a green light.

Sometimes, you have to run a Double NAT setup on some networks. Hopefully, the extra NAT layer will not create any new issues.