There's many ways an isp or business such as a university can block or filter p2p. It may apply to speeds, or blocking of ports or programs or making certain p2p clients illegal (unauthorised) on their system.

Endless Splendors check thru the proxies options b/c there's mention of various ports you might be able to use there. Another way to find out if a port is blocked is to test various port no.'s
This simple test is for port 6346. Using your browser go here: http://www3.limewire.com:6346/ The page should say 'Your test worked!'. What happens when you go there? If you can't get the page loaded then port 6346 is blocked.
Another simple test. Keep LW open!!! & then, using your browser go here: http://www.grc.com/port_6346.htm (Press Probe this port button) Does it say open or closed? If closed then set the test for a different port number. ie: type in the port no. in the space next to the jump button then press jump. Then do the test of the new port no. (perhaps best if your firewall is temporarily disabled or test with it (a) on & (b) off, same applies for NAT modems/routers to test directly by (c) by-passing these devices & (d) also with them.) Another test is to use http://koti.mbnet.fi/gfactory/ctest/ where you can test various ports but likewise you need to have LW open at the time for some strange reason!!!

(If the result comes back as Stealth then: There are only two valid responses a port can give when it is scanned: "open" and "closed". A port is considered "stealth" when it doesn't respond to a request at all. All the GRC port scanner does is fire packets out at your ports. If your port answers back, it will be listed as either "open" or "closed". if your firewall prevents your computer from answering back to GRC's port scanner, the port will be listed as "stealth".)