Equipment (Modems,Gateways)
Modems, Gateways, and Networking Devices
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Visitor

Static IP with Bridge Mode on Cisco DPC3939B and Sonicwall

Comcast recently swapped out our old modem to a DPC3939B and now our VOIP phones (non-comcast) are acting up.  The VOIP rep told me to check to make sure bridge mode was turned on for the new modem/router.  It was not.  But Comcast phone support tells me that because I have a static IP from comcast that I can't use bridge mode or else loose all connectivity to the internet.  I tried to be sure and yes I could no longer access the internet, but based on other articles here, such as the link below, I'm not convinced I'm getting the correct info from the rep.  I imagine ther are some settings I'm missing that should make this work.

 

I want the DPC3939B to act only as a modem, passing everything, including the static IP, to my sonicwall router/firewall.  In the past, I had the WAN of the sonicwall set to the static IP, DNS, provided by comcast. 

 

I don't like messing with the settings during the work day and when I call comcast at night, I seem to only get support who are reading from books but don't really understand the issue.  Any direction would be great.

 

https://forums.businesshelp.comcast.com/t5/Equipment-Modems-Gateways/Bridge-Mode-vs-Static-IP-with-C...

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Official Employee

Re: Static IP with Bridge Mode on Cisco DPC3939B and Sonicwall

Thank you so much for reaching out with your bridge mode query; the information that true bridge mode is not possible with a static IP is correct (https://comca.st/2vMILMg ) however, you can enable passthrough mode instead: https://comca.st/2UjPdo2 . Please let us know if that helps or if you need any other assistance Smiley Happy 

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Visitor

Re: Static IP with Bridge Mode on Cisco DPC3939B and Sonicwall

Ok thank you.  I setup passthru mode however when selecting custom security, there are no other options such a disabling the firewall.  Will that be ok?

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Official Employee

Re: Static IP with Bridge Mode on Cisco DPC3939B and Sonicwall

With your personalized network configuration, we're a little limited in how much we can advise but if there is nowhere to disable the firewall and your setup works as you need it to, that's fine by us! If you want me to try to log into the modem and see if I can find the option to disable the firewall, you can also send a private message by clicking on my handle (Comcast_Gina) and verifying the account with your name, the business name, the complete service address (including city, state, ZIP, suite number, etc), and the phone or account number, and I'd be glad to take a look Smiley Happy 

 

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