This morning, my [AirPort Extreme Base Station with Gigabit Ethernet (802.11n)][apbs] started crapping out on me. At first, I thought it was just a one-time glitch, and I cycled the power. Within a few minutes, however, it was frozen again.
[apbs]: http://store.apple.com/1-800-MY-APPLE/WebObjects/AppleStore?productLearnMore=MB053LL/A
I reset it, and this time I notice it goes through its paces, yellow light, syncs up with the WAN and we get the green light flickering with the network traffic. Then, ~30 seconds later, it goes dead. The light on the front goes out (not to yellow, totally off) but the lights on the ethernet ports on the back keep flickering. All of the wireless clients look like they still have signal *(4 bars!),* however, NO network traffic is going across any connections.
I tried a software reset from AirPort Utility. Nope. Revert to Factory Settings? Nope. Hard Reset? Nope. I gave up for a while, and set up my Mac Pro to share the connection over its AirPort card. (There's a [handy-dandy tutorial on this at Lifehacker][lh] if you ever need to do the same.)
Thankfully, a search of Apple's discussion groups later on led me to [this particularly helpful post][support] by Peter Paul in a thread about this very topic *that has been viewed over 13,000 times:*
> Running Airport Utility 5.2.1 I made the following changes:: Clicking the 'Manual Setup' button I first set the 'Channel' to 4 from the setting of 'Automatic' within the 'Wireless' tab of the 'Airport' section.. I next chose the 'Advanced' section and 'IPv6' tab and set the 'IPv6 Mode' to 'Link-local only'. Finally I downgraded the base station firmware to 7.2 (from 7.2.1). This is done by running the Airport Utility and from the 'Airport Utility' menu hold down the option key (control key in XP and Vista) and choose 'Check for Updates...' Place a check mark next to the version you require and click 'Download'. Select your base station and from the 'Base Station' menu choose 'Upload Firmware...'.
It's only been an hour since I did all three steps, but the Base Station already seems happier. Of course, the Base Station seemed to be pretty happy *without* any changes for the past 3+ months, so I don't know what set it off today. Yeah, it's a bit of rubber chicken-waving (and it might have only been one of the three things that really did it), but if you run into a similar problem and don't really have time to play "logic puzzle" with your Base Station, I'd recommend these steps.
[lh]: http://lifehacker.com/software/ultranewb/share-your-macs-internet-connection-wirelessly-283088.php
[support]: http://discussions.apple.com/message.jspa?messageID=6135544#6135544
*[WAN]: Wide Area Network