MTU is to low to play on xbox live?

I'm at Loyola university right now and they're help support is insanely unhelpful. I'm trying to hookup my xbox and ps3 to the internet but the MTU is too low. I have a wired connection going. On my computer the MTU was set at 1280 but that's wireless. Any suggestions on how to boost it up so that I can actually get online and playing again?