Xbox freezing on n900 router

It’s probably too late to help you but I am having a similar experience with the N750.  What were you using for a TV tuner(s)?  Were you using an HDHomerun Prime?  I found a partial work around which I posted here:

http://community.wd.com/t5/My-Net-Networking-Devices/N750-causes-xbox-360-freezing-locking-when-combined-with/td-p/622039