It sounds like your home and university networks are different types. I assume with your university, each user has his own login, whereas your home would have a general login that everyone uses? Perhaps in the new OS, the iPhone handles the individual logins differently?
It sounds like they are going to come out with a 4.0.1 version in the next few weeks that will recalibrate the reception bars you see on screen. Hopefully they will fix other bugs like this that people have been having.