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Fri, Dec 4, 2020 10:00 AM

Bridge Mode and Static IP

Before Comcast reads this and goes to reply PLEASE I already know with your system with a modem in bridge mode static IP is not possible on a device behind the modem. I'm making this post to talk with other Comcast business customers to see if they have a solution to this horrendous system I'm stuck using. Also yes pass through mode is the only option but pass through mode is still behind NAT.


Customers: Is there ANYONE on here that has gotten their business cisco modem AIO in bridge mode and their static IP working. I talked with a tier 2 tech and he informed me the static IP routing is RIP with auth key ( which is programmed into the modem software itself obviously. The tech told me he had one customer who did get it working but she refused to tell him, probably think she'd get in trouble or something.


Has anyone gotten bridge mode AND static IP functionality to work with a device behind the modem. It doesn't matter what device or vendor at this point I just need some real world configs to go off of.


Figured it is worth asking before I start looking into trying to get raw data at the coax level to see what the docsis frames look like and see if any info is usable related to the way static IP is negotiated to the modem.


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2 m ago

I too am running my Cisco DPC3941B, which is a bad modem. Just go to the explain the issue pretty well. I think it is unacceptable that Comcast Business forces us to use out-of-date defective equipment. Sure, I can buy my own superior modem without the issues, save $18-20/month, but they take away your Static IP. What's with that?


This is only a half answer, but may get you part way to solving your problem:

Option 1: If not super critical, it has been my observation that the dynamic IP address doesn't change very often, not acceptable in a mission critical application, but in some instances tolerable if not acceptable.

Option 2: there are services that monitor your dynamic address and will redirect a static IP address to that dynamic address. You can "publish" the static IP address and the service will monitor you dynamic address, when it changes it will redirect the traffic to the new dynamic address. A bit like redirection of websites etc. ( explains it better, I am sure there are others). 

Neither is really acceptable from the standpoint of you're already paying to have a static IP from Comcast. Very annoying.