Linksys router won't do "DHCP Renew"

[Achtung]

So, most of last night, my Comcast service was down apparently because of some kind of national DNS issue. Anyways, looks like late last night it came back up, and if I plug my cable modem directly into my computer, everything works fine. However, for some reason, if I use my router I can't connect. I have everything set up the way it was before, but doing a "DHCP Renew" just gives me 0.0.0.0 (I think the gateway is 255.255.255.0). Why won't it get an IP from the modem? Usually it comes up with 67.x.x.x I believe. Did Comcast do something to prevent my router from working? I've got the latest firmware on my router as well.

Appreciate the help.

 

[ArjSiv]

This is a typical tech support response, but have you tried powercycling your cable modem?

You can often diagnose whether the router is the problem by connecting it to another router and seeing if it obtains an IP.

If you still have a problem, here's a very technical way to diagnose it:

try connecting your PC to one of the router's LAN ports, tell the router to put your PC on the DMZ, and then install Ethereal. I believe broadcast traffic to the router should be visible from your PC using ethereal, you should see a DHCP DISCOVER coming FROM the router, then DHCP OFFER from the modem, DHCP REQUEST from the router, and then DHCP ACK from the modem.

 

[Achtung]

I've tried powercycling the modem, didn't help. And unfortunately I don't have another router at the moment to try out.

I'll try out your suggestion using Ethereal when I get home, hopefully it'll give me some more insight.

 

[Rottie]

Try re-boot your cable modem then do DHCP renew.

 

[Achtung]

I got home and, well, it just started working.:roll:

I don't pretend to have any idea what's going on half the time...

 

[avidfantabulous]

I am having a similar problem with comcast. There have been about 4 major outages here in the last week and now that those problems (DNS/DHCP servers) are supposedly solved, my router is unable to renew the DHCP lease automatically. If I force it to, it will eventually, but I lose connection every 2-3 hours now and I am not reissued an IP. I have tried a dlink router as well, but same problem. This problem just began a few days ago. The same setup worked fine before that. Comcast support suggested that I clear the DNS cache on the computer and then clear all cookies... I'm curious how many times you have to power cycle every damn thing in the house before they get a real engineer on the case...

 

[avidfantabulous]

I just spoke to a neighbor and he is having the exact same issue... maybe he has the EXACT SAME cookies I do...:evil:

 

[Fardringle]

I had the same problem yesterday on my Comcast cable connection. Cycling power didn't fix it so I ended up disconnecting the cable modem from everything for about 15 minutes. When I reconnected everything and cycled power again, my router came back up with a new IP address in a completely new subnet, and two of the three DNS servers were also different.

I suspect that Comcast has been making some addressing/subnetting changes on their network lately since a LOT of people have been reporting this problem.

 

[Rottie]

Blame on Comcast, not Linksys.

 

[avidfantabulous]

They claim to have fixed the problem now:

http://seattletimes.nwsource.com/html/localnews/2002245668_comcast19m.html