You are here

So to have a static IP with Comcast you HAVE to use their provided cable modem?

2 posts / 0 new
Last post
So to have a static IP with Comcast you HAVE to use their provided cable modem?

This is the first time I've run across this, but I usually work with TWC and Verizon where as long as it is a supported modem they don't care (or they don't charge you for the modem). I can't believe this is the case and according to Comcast TS it is SOP. Unfortunately I had already returned the old one to the store as per the Comcast phone CSR (who also said it wouldn't be a problem to have the static IP).

Is this really the case? Am I missing something on the technical end?

Given that in my experience they can't get anyone out in less than 24 hours, it seems crazy that a customer cannot purchase and have their own cold spare equipment on hand either. After all, this is business-class, right? We should assume uptime is important.

Also, they said that while anyone with existing TWC service will be grandfathered in, they won't allow it for new equipment or new lines. That's going to be a pain for a bunch of people (and an extra $13/month).


I didn't find the right solution from the internet.

whiteboard animation

I run a DHCP server for an

I run a DHCP server for an MSO that takes care of modems and CPE static IP's.
I attach the static IP to the mac address of the device behind the modem. Not the modem itself.

It could be that the lease simply needs to expire on the circuit id that held the cpe mac to the modem mac. Once that's done, I would think that it would pick right up.

Whenever we swap out a modem for a business that has a static IP, I have to delete the current lease to clear the circuit ID--otherwise, the CPE when it comes up behind the new modem says "hello DHCP server, here I am" and the DHCP server says "you're supposed to have this IP address, but that IP is currently in use by another circuit."

I guess you could say its the docsis equivalent to 'all circuits are busy.'

This should be the case even if you're authorized to set your IP manually on your device. Perhaps just get someone in tech support to clear your current lease out, plug your equipment in again, and see if it takes.

Just an idea though. I highly suggest you just contact them, insist on tech support, and not take my word as gospel.