At home I have a peculiar networking situation, primarily because Comcast’s modems are a pain in the ass, but secondarily because Motorola’s models are a pain in the ass – because Comcast chooses to recommend these Surfboard modems.
I have an SB900 which is the 900th iteration down the SB line and its quite a complicated bastard of a system. On the right you will see a diagram of my local home network, and the overview of how crazy things are here =
I hope for your sakes that you are able to avoid dealing with this, but please keep this in mind – LET YOUR MODEM BE A MODEM! Turn off NAT and you will be able to effectively remove your modem from the loop. The SB900 is not a child’s router, as it takes some frowning to be able to get yourself setup initially, but one good thing to note is that if you do run into trouble with configuration you can reset the configs to defaults without losing your Wireless settings, which mind you I have also turned off.