by WaCableTech - 8/28/10 6:52 PM
If you go to 192.168.100.1 you should get at least a signal page and possible a log page you can post, I can help you more from that.
Modems can have issues for a variety of reasons, but it sounds like the more plausible one, from what I can guess ,is your upstream is having problems and the extra split is pushing it over the limit.
Also when you have the single line connected, can you perform a
ping www.cox.net -n 150
from the command line and post just the results,