The Surfboard is a line of cable modems made by Motorola. A cable modem is the network interface between a computer and a television cable system that provides Internet service. One of the features of the Surfboard modem is a set of online diagnostics. While this is mentioned in the product literature, unfortunately there is little or no information in the user guide on how to access it or use the information it provides.
Finding the Diagnostics
The Surfboard modem generates its diagnostics as a set of HTML pages that can be viewed with your web browser. The main page is accessed by typing the following address into the browser's address bar: http://192.168.100.1/.
Below the main page are six sub pages that are accessible by links at the top and bottom of the main page. Each subordinate page provides the following types of information:
Status: The startup test results. "Failed" is displayed if there was a problem at startup. Signal: The downstream (input) and upstream (output) signal data characteristics. Addresses: The cable server settings. Configuration: The modem's manually configurable settings. Logs: A historical record of status and messages and the time each one occurred (in GMT). Help: Some rudimentary troubleshooting tips
To update any of the measured values on these pages, click on your browser's refresh button and it will report current values.
What to Look For
The Status page should not report any failures.
The Signal page should have solid power and signal-to-noise values. Downstream power is nominally 0 dBmV with acceptable values being in the -10 to +10 range. The signal-to-noise ratio may be 50 dB or higher, but the modem can operate with values as low as 35. The modulation type should be QAM256. Upstream power should be in the 45 dBmV range with a symbol rate of 1 MB/s or higher, depending on the quality of your service.
If the diagnostic pages show results that indicate problems, check the following:
The connectors on the coaxial cable from the wall to the modem must be tight.
The power lamp on the front of the modem must be on with the "Send," "Receive" and "Online" lamps on or blinking.
The network cables must be secure. For Ethernet, the cable between the modem and the computer should be connected and locked, and the LEDs at the connector should be on or blinking. If the connection is USB, make sure the connectors are pushed all the way in.
The standard resolution procedure if no hardware problems are found is to reboot the modem by disconnecting and reconnecting its power plug.
Consult the Cable Modem User Guide for additional information.
It is a good idea to write down values from or save an electronic copy of your diagnostic page readings while the modem is operating correctly to use in the future if problems are suspected.