I've been playing the game with no issues for as long as it has been out, and now I am having the same problem. It started maybe two weeks ago, I would be playing, then suddenly there's lag, and I'm out of the server. There hasn't been a day that has passed without it happening, and my gametime has dropped by a large percentage because of it.
I have tried all of the fixes listed. I don't have two rgl_config.txt files, and in the one my secure connection is set to 0 (set it to 1 once out of desperation, did nothing). Tried the single threading thing. Tried changing number of max connections to 8 as advised elsewhere, and all it did was not let me even see a single server (the server I play on typically has a maximum of maybe 40 players, and that's very rare). I've tried uninstalling and reinstalling the game. I've tried playing outside of Steam (I bought it from Taleworlds directly).
Numerous posts on other threads and forums where people were complaining about the issue suggested that the router was at fault - well, there wasn't anything that changed on my router since the problem started, but after being advised by an admin, completely reset my router and set it all up again. It seems to have helped some since I can now play for about ten minutes before it kicks me out again. Someone mentioned keeping an online service going while I'm playing, but I have two flatmates who are nearly always playing something online while I am, or browsing, or downloading, so that's not a solution. My ping remains steady at about 55 - and when I am kicked out of the server, there is no effect to our 'net connection, like some have been reporting.
Not sure where else to turn, or what to try... I seem to have exhausted the list of suggestions. Any help would be greatly appreciated...