As suggested in other threads:
If you join pantheon and find a matchup that starts to connect you people together, wait at least, eltsay thirty seconds. If there is still people that are not connected to anyone wait a fifteen seconds more and if not helping cancel.
As said, its known an issue. Anyone on the list of your peers to join the match if even one isnt joined to anyone the match wont launch also if ANYONE else quit it wont launch. So if you see anyone leaving you better hit cancel and start another search, yours wont be launching.
For some reason the lobby/pantheon keeps on claiming to search for players or even matches sometimes when it simply dosnt, it just that servers are so overloaded it seems to take 2-5 minutes for the servers figure this out and then they give you a NAT error if someone quit or there was one of those no connection people with you. To speed things up, cancel... reque... and hope you find handful of people whom can all connect and dont quit up prematurely. It sometimes takes a little while for folks with bit longer pings to get even one connection setup... but it happens, been there.
Just no sense staying minutes there, thats kinda a way how you can get to pantheon matches faster. Minimize your frustration to quit queuing for lost cause matches and seek one that might actually launch. I can tell you that even us that get into matches, the success rate of a actual 'match' being queued to launch is perhaps what? Good if its one in ten, occasionally little better sometimes worse.