multiplayer difficulties

So got red orchestra 2 recently, single play works great, but i cannot get multiplayer to work.

What happens is i join a server, select a team, class and start to play, for 30 seconds every thing will go fine, then it fucks up. all the players just keep performing whatever action they were when the problem occured, example walking slowly shooting or running into a wall, but i can move around fine, and my ammo never runs out.

im pretty sure i have the most recent patch, and while it is working dosent seem to be much lag.

any one know how to fix this?