Can you most more data regarding your configuration?
1. Grab information about your modem's current signal levels. Generally accessable via: »
192.168.100.1 on most cable modems.
This guide will tell you if your signal level's are within acceptable range.
»
Comcast High Speed Internet FAQ »
What should my Signal Levels be?2. Open up a command prompt and run the following:
Windows: tracert www.google.com
Linux/MacOS: traceroute www.google.com
3. Ensusure your tests are done on a wired connection for speedtest.