So I have my network setup to use multiple devices, 1 ps3, two xboxes, 2 desktops, 2 laptops etc.
The only issue I have been running into is when I'm playing online when both xboxes are online.
My rules were setup accordingly to the Sticky for Xbox Live.
My setup is a bit crazy too, I have the Cisco DPC3825 from Shaw which I've setup as a fake bridge and then the rest of my devices are hooked up through the Router.
Seems to happen most often with Capcom Games.
EDIT: Forgot to mention Im on 1.22NA