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.
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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?
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