Unity networking game keeps crashing

Hey hey, I've got a networking game going everything works great except, it crashes when I'm playing with more than two computers. It freezes, closes, and then a run-time error window appears. I'm wondering if it has something to do with the port, because it crashed after like 5 seconds of playing with the port: 25001, but then when I changed it to 25002 it played for a good 4 or 5 minutes before crashing. If anyone can at least give me some kind of direction or something to work off of, that'd be great. Thanks.