This is a problem that I know multiple users have recently experienced, but it's gotten to the point where the game has literally become unplayable at times, because you cannot enter a room.
When a room is selected, the entry screens are shown (loading [map], optimizing players etc.), then the game brings you back to the lobby without warning.
The issue does not occur all the time obviously, as people are still playing, however for many users trying to enter certain rooms, the game does not allow them to access most rooms.
I've had this problem quite a bit, and I know others have because of the connecting/disconnecting log in the game chat. Users who are unable to enter the room appear as being connected, but never actually end up in the game. Because they try and connect to the same room over and over again, the log just keeps saying the player connected.
It may not happen for everyone, but I know that me and a friend who play together often have consistently had this problem in the past 2 days. Feel free to check it out, but please be aware it may not affect all users.
I've tried the general bug advice already (refresh page, log out/in again, try a different room, different server) and usually this does nothing.
I've also noticed occasionally after a victory, the game will show you have been defeated, which is extremely annoying for people trying to level up and get money.