Port 3724 I believe.

For port forwarding, first thing you must do is set up a static ip address: Setting up a Static ip Address

Then choose your router brand & model -> PortForward.com - Free Help Setting up Your Router or Firewall click on the model -> click the skip this add at top right of next page -> choose World of Warcraft from the alphabetical list of purposes for port forwarding.

At university they may well have various ports blocked. Else they have a p2p shaper .. which might apply to games & sharing programs. It can either shape the bandwidth or totally block them. Such shapers can detect the type of protocol that is being used to communicate with other gamers/p2p sharers.