Rather than make a new post I may as well add this here.
Lets do a test, especially if you have Comcast. If you are using a Linksys Cable MODEM click on this link. It most likely will work on others also.
http://192.168.100.1/
This will take you to the modem controls and you click on the "Connection" link. When the window opens what does the numbers say for Upstream Power?
Mine says 52.7dBmV. Upstream Power shows the level of the signal from the cable modem to the provider. This number should be lower than 55dB. The lower the number, the better your connection.
Downstream Power shows the power of the signal your cable modem is getting. Mine is -2.0dBmV. The level of the downstream power should be -15 to 15 dB; however, it is best for that level to be in the -8 to 8 range.
Guy