🙂
OK, it is possible the Ethernet port on the Express is simply NG. To completely rule out that possibility try another computer, even a Windows computer running its version of AirPort Utility, and another cable. The fact your computer connects to your university network means its port is working.
Surges such as those resulting from nearby lightning storms can kill an AirPort's Ethernet port.
Edit: I want to make sure we are understanding each other. How are you communicating with the Express? If it's wirelessly and "Ethernet unplugged" is appearing as an error, then turn off your computer's wireless and connect it directly to the Express with an Ethernet cable. If you can communicate with it using AirPort Utility then clearly its Ethernet port is OK.
Message was edited by: John Galt