MTU Setting

[Verby]

I was playing street fighter on xbl today and was suddenly disconnected and was unable to reconnect to live. I ran a connection test to see what was wrong and got a message saying my MTU setting was too low. I am currently living in university halls of residence and have had no problems with my xbox or live up until this point. The suggested method of dealing with this was to go onto my internet browser and configure my router and change the MTU manually, which I am unable to do as was stated earlier as I am living in halls of residence.

Is there any reason why this would have just randomly happened? Has anyone else had a problem with this before?
Any help would be appreciated. Thanks.

[Cheerios]

The only thing I can think of is that someone with administrative access could've changed the MTU on the router, but I can't think of a good reason to reduce it.