Currently Being ModeratedMar 21, 2012 6:28 PM (in response to David Stahl)
Your modem is not distributing IP addresses. The 169.254.51.249 address is "self-assigned" and worthless. As you indicated in step 7, nothing else is going to matter since your Extreme is not connected to the Internet.
Your modem configuration and status pages ought to look like this:
Regardless of what your cable company says if the modem is not distributing IP addresses it's not going to work. You might need to get them to replace it. Until then try powering it down for a good long time, at least several minutes, and let your Extreme rest also. Then, power up the modem, wait a few moments, followed by the Extreme and all other network devices in that order.
It sounds as though you changed the Extreme's settings so you may have to verify them again after doing this. Following that it may be required to perform another power down exercise.
Leave the Extreme connected to the modem during this power down. Connecting anything else to the modem will require that you power it down again so it "forgets" the device that was last using it.
If all else fails, perform a "hard reset" on the Extreme. It is possible an internal parameter has become corrupted, in which case the "hard reset" is the only way to clear the fault.
Make sure you do it properly so the "hard reset" is effective: http://support.apple.com/kb/HT3728
Currently Being ModeratedMar 21, 2012 6:27 PM (in response to John Galt)
Thanks for the reply, I'll try the extended power-down and let it sit over night. I will go through the original setup again before shutting it down and leave everything connected as you've suggested.
I know that my laptop gets an IP address when I plug it directly into the modem. I've read on other forums that this motorola may not actually give out IP addresses but it may come from the ISP (Comcast)'s own DHCP servers somewhere else. Not sure if that's true, or if that was a change recently on their end?
I should also add that my Surfboard diagnostic screens look like what you've posted and it does seem to work if I cut out the airport extreme.
Currently Being ModeratedMar 21, 2012 6:46 PM (in response to David Stahl)
In addition to its own IP address the SB5101 distributes exactly one address to whatever is connected to it - generally, a router. Those IP addresses do not originate from beyond the modem.
Confusion understandably results when trying to diagnose problems like yours. If you bypass your Extreme by attaching a computer directly to the Surfboard so you can get online, then subsequently detach your computer and reattach the Extreme, it is certain not to work because the modem is not a router. It gave its one and only IP address to your computer and will continue to look for it at that address. Since it is no longer there, nothing happens. In the meantime your Extreme gets ignored, gives up, and assigns itself an IP address so nothing happens either. That's the reason for the power down.
I have heard anecdotes that some modems that take a long time to reset themselves; thirty minutes or more, but that seems unreasonably long.
Currently Being ModeratedMar 22, 2012 5:00 PM (in response to John Galt)
I tried leaving everything unplugged for 8 hours and then for 13 hours after doing hard-resets. Still didn't work.
I bought the cheapest Linksys/Cisco wireless router I could find and it worked perfectly out of the box with my cable modem. Any chance my Airport Extreme is busted and if so, how can I tell for sure?
Would someone at an Apple Store be able to confirm that it's failed?
Currently Being ModeratedMar 22, 2012 6:42 PM (in response to David Stahl)
Yes, you did everything I can think of and the only conclusion I can draw is that the Extreme's WAN port is NG. This would appear consistent with everything else you did.
It is strange that the failure would have coincided with the power going out.
The Apple Store ought to be able to confirm your diagnosis.