Airport Extreme, no internet I have an Airport Extreme (4th generation) with firmware 7.5.2; it has been working fine for a long time, but stopped working properly after a brief power outage a couple of days ago.

The router powers up normally and shows a solid green light, alas connected devices (a notebook, apple tv, and a couple of iphones) get "no internet".

using the Airport Utility i have verified that the WAN link is up and the devices are accociated with the network; I have also called the ISP and verified that the IP lease is ok.

I have tried resetting the router several times, as well as powering down different elements of the network and restarting them in different order.

i should mention also that my service is over a fiber network, so if I plug the Ethernet cable directly into my notebook everything works fine - the ISP is not to blame.

To me this seems to be a problem with the Airport router itself, a software / firmware problem of some sort - has anyone come accross anything similar?
To start I'd do a reset to factory settings. This support document tells you how.

From there I would start by then connecting a Mac using Ethernet and seeing if you can get it connected to the 'net. 

First would be to establish that the Extreme is handing out IP addresses via DHCP. When you look in System Preferences > Network the Mac should have an IP address from the Express (probably 10.0.. or 192.168..), not a 169...* self assigned IP.

Then can you ping the Extreme from the Mac. Then can you ping your modem. Finally, can you ping "www.google.com" (which will also show that you have DNS working).

If any of that breaks then check the settings on the Extreme until it does and you should be good.