If you want to have the best network in your house, be prepared to do most of the tech work yourself..I recently had an issue where my modem kept restarting...on calling Comast they said it was my modem (which I own)..I did not bother arguing but started some research..
This site was the most help
http://www.dslreports.com/faq/cabletech
In the end my signal was poor because it went thru 4 splitters to get to my cable modem..I ended up putting my modem right at the 1st splitter in my garage and running cat 5 to my modem...my signal has been better then ever and no more restarts...
keep in mind that my cable modem was fine for years and then recently the signal problems started...I'm guessing that comast network reduced thier signal somehow but who knows?
anywho, be informed and do your homework and you will be fine...