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Ongoing DHCP problems

New Poster

Ongoing DHCP problems

I read about this exact same problem in this locked thread, and my symptoms are exactly the same.

Just like the OP, I’m an IT pro, 20+ years. I’ve gone as far as to replace both my modem and my router, only to get the exact same issues. NetGear CM1000 routers, I’ve used everything from an ASUS AC3100 router to a SOHO CheckPoint firewall. The symptom is always the same:

Sudden loss of DHCP lease, and an inability to renew. The ASUS goes so far as to say “your ISP’s DHCP server is not configured correctly.” At some point, it will magically start working again, at least until the lease expires and I roll the dice to see if it will respond again.

The CheckPoint logs didn’t go into detail, but I’m about ready to drop an Ethernet tap and post the entire capture file where we can get to the bottom of these problems - they seem to be very widespread, and typical of something within Comcast’s infrastructure or architecture. 

The calls to Comcast are getting old - if I had competition to choose from, I would have dropped Comcast by now. Has anyone learned exactly what the cause of this is?

New Poster

Re: Ongoing DHCP problems

I’m in the SF area and I’m having that exact problem right now. I’m not getting assigned an IP address through DHCP.
New Poster

Re: Ongoing DHCP problems

I've swapped out the modem and router. Still a (different) CM1000 from Netgear, and an ASUS 3100 instead of my CheckPoint device. 

Same problem. "Your ISP's DHCP does not function properly". 

As widespread as this issue seems to be, it would appear that maybe Comcast needs to reconsider its architecture. 

New Poster

Re: Ongoing DHCP problems

Same problem here last night into today. I’m a CCIE So I know this stuff dead cold - Comcast, you need to do a better job on this issue, and educate your call center people to do more than just repeat the same reset process the automated phone system does already.
Expert

Re: Ongoing DHCP problems


@Offacough wrote:

I read about this exact same problem in this locked thread, and my symptoms are exactly the same.


The calls to Comcast are getting old - if I had competition to choose from, I would have dropped Comcast by now. Has anyone learned exactly what the cause of this is?


Well, there's this bit at the bottom of the locked thread - 

 

UPDATE: Definitely not DNS related and looks to be completely line/splitter related at this point based on the fact that it has disconnected me pretty much every 15 minutes for the last 3 hours while the damaged frames add up on the OFDM channel ... If your modem power/SNR levels look normal for the most part and the disconnects you are seeing happen indiscriminately and at any given time for random intervals of time, I would get a tech out there. I suspect you have ingress coming from somewhere that comes and goes like mine.

 

Please post your modem stats as indicated in Information Requested for Connection-Related Posts .

Plus, you can do a bit of troubleshooting yourself as indicated in Xfinity Internet Connection Troubleshooting Tips

 


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