Five months later and it happens again... my internet is down. The router (an SMC Barricade) that I hooked up during the previous debacle is now unable to obtain a DHCP lease from Comcast's network. This always seems to happen on a weekend...

So, I replaced the SMC with my Belkin. This is the exact same Belkin that Comcast's first and second level technical support insisted MUST be malfunctioning last December because it was unable to obtain a DHCP lease from their network at that time. It works just fine. I'm back up.

The SMC goes into my toolbox - inevitably in a few months I'll wake up and my Belkin will again be unable to obtain a lease from Comcast, and I'll replace it with the SMC, which will work just fine.

My previous explanation of this problem erred in terms of providing a lot of irrelevant technical detail about the difference between the DHCP process that I was seeing from my laptop and my Belkin. I'm now operating off the exact same Belkin that was not getting a lease in December, and it performs DHCP in exactly the same way that it did in December, but it now gets a lease just fine, and I now have a different device that cannot get a lease.

The simplest explanation is that Comcast's network is refusing a lease to my router's MAC address. Other MAC addresses can get a lease just fine. This condition appears to be temporary, but it lasts more than 24 hours and thats as long as I'm willing to wait for it to clear.

This is most likely a configuration problem with their DHCP server - my first guess is that it is not allowing devices with old leases to obtain new ones, but of course I can't troubleshoot this myself, and Comcast refuses to take it seriously. If I was a sadist I'd call Comcast's technical support so that they can tell me, again, that my router must be broken. I've got better things to do today.

I wonder how widespread this problem is. I wonder how many Comcast customers go through router after router thinking that they must be pieces of junk that fail constantly, when, in fact, there is a problem with Comcast's network. Hopefully, some victims of this problem will find this thread and be saved a lot of frustration.

RE: Comcast's DHCP is STILL broken