Change subnet for Comcast Business Router

To change the subnet configuration on a Comcast Business Router (Cisco model number DPC3941B), log into the router. The default subnet used by the router is with the router's IP address being with a subnet mask of So, if the default configuration for the router has not been changed, you can log into the router by connecting a device to it that will get its IP address by DHCP and then pointing a browser to When you are logged into the router, you will see a window labeled "Gateway > At a Glance," which is a selection under "Gateway" in the selection list at the left side of the main window.

Comcast Business Router Gateway
At a Glance

Click on "Initial Setup" on the left side of that window to configure the Local Area Network (LAN) Internet Protocol (IP) information that will be used by the router.

Initial Setup

When you are finished making configuration changes, click on the Save Settings button. You will then see a "Are you sure?" window advising you that "Changing Gateway IP or any DHCP setting would reset the gateway." You will also see "WARNING: Gateway will be rebooted! Incoming/Outgoing call and internet connection will be interrupted!" Click on the OK button.

Related articles:

  1. Resetting the password for a Comcast Business Router
  2. Remote Management of a Comcast Business Router