merged the threads... please do not start a new thread for the same issue....
If you configured your router such that you can no longer access the web config page, your best option would be to do a factory reset, and configure it again.
If you are having trouble with a VOIP phone on the school's network, then contact the net admin (as has been already suggested), and see if they are able to solve the problem. It could be that there is a port blocked that is causing the issue, in which case, you are SOL unless the network Admin will unblock the port for you.