Equipment (Modems,Gateways)
Modems, Gateways, and Networking Devices
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New Contributor

Port Forwarding Problem with DPC3941

We are using the Comcast (Cisco) DPC3941B router/gateway on a small office network.  We need to forward Port 443 to the server.  The IP value of the Comcast gateway is 192.168.16.1.  The fixed IP value for the server is 192.168.16.2.  Whenever I try to create a port forwarding rule on Port 80 or Port 443 to the server I receive the following error message:  "Failure!  Please check your inputs."  

 

The Comcast box functions as the DHCP server for the workstations on the network.  The value range we have specified for DHCP IP assignments is between 100 and 199 (192.168.16.100 to 192.168.16.199).  

 

I am not sure what is wrong here (having done port forwarding numerous times on other devices).  Is it that the fixed IP of the server (the "receiving" machine of the port forwarding) is outside of the DHCP assigned IP addresses (192.168.16.2 vs. 192.168.16.x where "x" is great than or equal to "100")?  Or is the problem due to the IP version we are employing (v4 and not v6, although there is a section of fields for v6 address information on the gateway port forwarding screen that is partially greyed out).

 

Our entire remote access system depends on this port forwarding function, which employs a static IP from Comcast.  Most of our staff is working at home and can only work via remote access (which itself is not working due to the port forwarding problem).

 

Any assistance your can offer will be greatly appreciated.

 

John

 

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Official Employee

Re: Port Forwarding Problem with DPC3941

Hi there, thanks so much for taking the time to reach out to the Digital Care Team here through the forums and we are so sorry to see that you are having issues with your equipment and you have reached the right team to help get this taken care of. Can you please send us a private message with your name, the full address, and the account or phone number? 

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New Contributor

Re: Port Forwarding Problem with DPC3941

Sure.  Please send me instructions on how to PM (Private Message?) so I can get the requested information to you.  Thanks.

 

John

 

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Official Employee

Re: Port Forwarding Problem with DPC3941

Of course!

To send a private message:

  1. Sign in to the community.
  2. Click the message count or envelope icon to go to your Private Messages Inbox.
  3. Click New Message.
  4. Enter the recipient's name in the Send to
  5. Enter the subject for the message in the Message Subject
  6. Type the reply in the Message Body
  7. Click Send Message.
  8. You can look for the messages you've sent in the Sent tab.

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New Member

Re: Port Forwarding Problem with DPC3941

John:

Port forwarding on the DPC3941 is sporadic at best. As IT for my company, I have tried many times to open ports to my internal resources. To illustrate, I'll relate a call I had with a long time Comcast rep who prided himself on being able to fix most problems. When I explained to him in detail what I had tried that didn't work, his only response was "Well, in all my years I've never seen or heard of that problem". I went on to explain that I had spent several days trying to get ports 8000-8003 open to access my security cameras. Nothing I did worked and I accused him/Comcast of being told to tell customers port forwarding works while denying my experience of the problem. 

 

Just yesterday I tried opening one single port (22124) in my DPC3941 (we have a business account at home) and NADA! Modem would say port was open but no online port checker could see it as open. I tried port triggering thinking that maybe that's tied to port forwarding somewhere deep in their firmware - NOPE! Having been down this road before, I simply gave up and will post andwhere I can how bad Comcast support is.

 

Good luck!

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Official Employee

Re: Port Forwarding Problem with DPC3941

Thanks so much for taking the time to reach out to us regarding your port forwarding issues. I very much appreciate your patience and greatly apologize for the delay in our response. I know how important the services are to your business and we want to do all that we can to assist. I would love to get to the bottom of the port forwarding issues. Can you please reach out through private message with your first and last name, business service address and account number or phone number? 

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New Contributor

Re: Port Forwarding Problem with DPC3941

Thanks for your comments.  We have also had sporadic success in implementing port forwarding with the DPC3941.  Do you know if the DPC3939 any better in this regard?

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