So this happens on all servers with BattlEye anti-cheat enabled. This happens regardless of whether I have mods or not, or if the server has mods or not. I have tried basic stuff like portforwarding a few ports, unsure if they were correct or not though and things like allowing it through my firewall, verifying the integrity of the steam cache, reinstalling BattlEye, running as administrator or manually installing it. Nothing's working so far and one of the main elements for ArmA 2 for me is multiplayer. I don't want a good game to be wasted money.
Edit: I'm running Windows 7, and I own the steam version of the game. I don't remember if this is the case but I believe it happened on my older computer before I got this particular computer. New thread because all others are several hundred days old and none of them seem to have my exact problem or a solution.