I had Comcast (local cable internet supplier) service my exterior line today.
The serviceman used my browser to display the Motorola modem readings at the end of my house line.
- Enter 192.168.100.1 in your browser address line and hit enter
- Click on Signal on the left side.
The Downstream Power Level is the most important reading (just remember that -4.0 is better than -10.0). You might still be able to use the internet with a -13 reading but it should be above -10.
SNR (signal to noise ratio) is also important it should be above 33dB.
Readings outside this working range can be caused by a poor signal from the cable supplier or from bad connections (too many splitters) or too long a cable run in your house. Each splitter cuts your Power Level in half. 50 feet of marginal quality or poor connection on the cable might drop the signal by 4 dBmV.
Motorola Surfboard SB5120 QAM 256 (Working range)
Down Power (between -10 and +10 dBmV)
SNR (higher than 33dB)
Up Power (between 30 and 55dBmV)
Thanks to xpcman for this tip on the forum.