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Tuesday, June 22nd, 2021 3:50 AM

Cannot get static ip block to work with external router

Hello, I have a block of 5 static ips and I'm trying to use an external router (RV340W), however I cannot get the static ips to route.  I put the comcast router into bridge mode (Advanced).  If I set the wan of the router to dhcp, it gets an external dynamic ip,  all clients can get out to the internet, but none of the 1 to 1 NAT rules work for the ips in the block.  If I set the wan to the static ip information that I see on the My account page I do not get internet access at all.

Here is what comcast account shows

  • Static IPv6 Information2603:3023:a25:XXXX::/XX
  • Static IP Range96.78.XXX.XXX - 96.78.XXX.XXX
  • CIDR Block Number96.78.XXX.XXX/29
  • Gateway IP Address96.78.XXX.XXX
  • Subnet Mask IP Address255.255.255.248

Cisco router wants 

  1. Static IP (I'm assuming this is the first address of the CIDR block)
  2. Subnet: (
  3. Default Gateway: Using the one provided
  4. DNS: providing standard comcast dns,

Official Employee


24 Messages

3 years ago

Hello, @Mindcloud. Thank you for reaching out about the connection issues happening when involving the router. You may find this link useful to get things working, If you need further assistance past the steps in the link please feel free to send us a chat message with your first and last name and the service address.


Here are the detailed steps to direct message us: 
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 • Click the "New message" (pencil and paper) icon
 • Type "Xfinity Support" in the to line and select "Xfinity Support" from the drop-down list
 • Type your message in the text area near the bottom of the window
 • Press Enter to send your message