A lot universities do close certain ports especially for stuff like IRC file transfer and P2P, normally a quick change sorts this but it is not so easy for the DS/PSP.
Some also implement some form of login (either upon aattempted access or via special software) and/or mac address filtering which will screw any plans up.
Normally if you have a word with someone in tech support/computer services you can come to some form of arrangement (a lot of universities will not restrict common areas as heavily but in places like libraries you will come unstuck).
Failing that you could buy a wireless adaptor and use a laptop/PC, not the best solution but it will work.