I have the exact same problem. I don't think it's router related because I managed to play all day yesterday and today. At 16pm I got kicked for the first time, with the kicks becoming more frequent. I tried a bunch of things, reinstall, rebooted PC, editted some files... Nothing worked.
What scares me most is that some people have been having this issue for over a year but there's no solution yet. I bought the game yesterday (the entire 4-pack on steam) and I will ask a refund if this does not get fixed. It's ridiculous that some people haven't been able to play for over a year and their have been so little attempts to track this issue down! I'm very frustrated and I hope that this will be resolved asap.
I'm very glad I bought the game and supported the devs by doing so, but if this does not get fixed, I won't stand for it. If you want any information, please ask and I will give. I know you guys want to fix this just as bad as I do.