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Bridge Mode for DPC3939B

consulotech
Visitor

Bridge Mode for DPC3939B

Hopefully I got this in the right forum topic. 

 

I just signed up for Comcast Business Class Delux 150 internet with 5 static IP block. Before I had a residential line with a Motorola SB6141 connected to a Linksys WRT1900AC router. I was using Dynamic DNS for hosting my server up to the web and it worked great. 

 

The comcast installer used a Cisco DPC3939B commercial gateway for the new install. I need to dumb it down so I can use my superior WRT1900AC router. I tried putting it into suedo bridge mode by turning off DHCP, DNS, Firewall, port forwarding and NAT. I then set a static WAN IP on my WRT1900AC with the same port forwards I had before. 

 

Internet works great, however my port forwarding is not working. If I try to hit the WAN ip, I get nothing.

 

What am I missing??

 

I would prefer to ditch the DPC3939B and keep my Motorola SB6141, however my understanding is Static IP's won't work if I do so. 

Trusted Forum Contributor

Re: Bridge Mode for DPC3939B

Hello consulotech and welcome,

 

If you put any Comcast or Industry Standard Gateway (in your case the DPC3939B) into true bridge mode then you will not be able to use your internal static IPs, your DHCP server, your private or public wifi. You can certainly use your mentioned sb6141 modem as a customer owned modem (COM), however, Comcast only supports the boot file loaded into all COMs and all other technical support is provided by the manufacturer.

 

Hope this helps you out. 

 

consulotech
Visitor

Re: Bridge Mode for DPC3939B

Thank you for the response!

 

 

When you say "If you put any Comcast or Industry Standard Gateway (in your case the DPC3939B) into true bridge mode then you will not be able to use your internal static IPs, your DHCP server, your private or public wifi." you are referring to the DPC3939B not being able to perform these function correct? Certainly my WRT1900AC router sitting behind the modem can perform DHCP and wifi functions on my internal network. 

 

I was under the impression if I used the SB6141 modem that my WAN static IP's would not work, am I incorrect in that statement?

Trusted Forum Contributor

Re: Bridge Mode for DPC3939B

Yes, I am referring to any Gateway being in true bridge mode will disable all internal functionality. This means that this device will be only pass-through device providing it WAN address only.  Yes, you cannot use any Comcast static IPs in any COM.

 

consulotech
Visitor

Re: Bridge Mode for DPC3939B

I solved the issue! I had the default gateway ip on my web server set to the comcast modem instead of my router by accident. I changed the default gateway ip to my router ip and presto, I'm available from the WAN!

 

So modem bridge mode to router works like a charm. Thanks for the feedback!

Trusted Forum Contributor

Re: Bridge Mode for DPC3939B

Hey, glad you were able to get up and running. Smiley Happy