I have a theory... a theory that I will present here despite its slightly technical nature.
I think that many players on certain networks, specifically at universities, have trouble in general because they are trying to crack down on file sharing that kills bandwidth and is morally questionable. So, they restrict everything but port 80, which is usually reserved for web pages. (File sharing would normally happen on other ports and is therefore easily blocked by the administration) So, port 80 works for many players, except that I think they FURTHER restrict things by checking if the port 80 traffic is really web traffic.
In the past, the game used an HTTP (web) connection to do the initial security check allowing the game to then connect to port 80. Now it is still doing the security check on port 80, but isn't using HTTP. Your network may see the traffic as non-web, even though it is on port 80, and restrict it. This would explain a lot of these problems.
Does any of this ring a bell?
I am working on some changes today that may fix or at least give me more information about this. Please check back here! Thanks!