How to Unlock Cable Modems
Your cable modem will connect a browser to the Internet without adjusting any settings. Unlock the cable modem when it is not connecting to the Internet due to an IP issue, or if you want to change the connection settings or access hidden features.
Locate the serial number and the web address on the back or the bottom of your cable modem.
Connect to the Internet, then type the full web address, followed by the serial number, in the URL field at the top of your browser. Press the "Go" or the "Arrow" next to the URL field.
Enter the default set up code: "admin" or "0000" into both the "User name" and "Password" box. Click "OK."
Enter a new username and password on the next screen to unlock your cable modem. Click "OK."