This week I purchased an AirPort Time Capsule and attempted to set up my own network in my dorm apartment. The network at my school has two options, one requires me to login with my school ID and password every time I get on the internet and the other is password protected WPA2 which asks for the same information (ID and password) but logs me in without having to type my info in every time.
I plugged my Time Capsule into the Ethernet port on the wall and set it up. When I did, the school had me register an IP address to it, I started using it and everything seemed to be fine, but then I got my older Mac and my new MacBook Pro Retina connected to my Time Capsule network and the new MacBook would disconnect every few minutes and sometimes it would reconnect, sometimes it would give me an "!" in the WiFi sign. Also I tried connecting my Apple TV to it, it said it was connected, with an IP address and everything but, it wouldn't let me use any content—no YouTube, it wouldn't sign into iTunes etc. I have no clue what to do.
Best Answer
Since you only have 1 IP address from the school, you need to make sure that your airport is setup in NAT mode, and not in bridged mode. You'll need to make sure it's giving out DHCP addresses as well, and you may want to make sure it's not in a range used elsewhere on campus so that you don't run afoul of weird routing issues.
I suggest the 172.16 range since it's rarely used by institutions in my experience, YMMV.
Let me know if this is helpful!