Your school does (it has to) have a specific page about the vpns they will allow to connect, and not allow to connect, to their vpn networks. It's probably linked to the vpn instruction page. I'm looking at this page for an institution close to me as we speak.
Similarly, an IT guy from another institution told me--a while back-- their policy was to block all vpn's from home trying to access the school. If you gave the IT dept a 'heads up' that is was you, then they would unblock you.
That's all I think I know. Hope it's a starting place.
