Every co-op match I join into I lose connection with in under 2 minutes. My internet's good and the latency and ping in-game aren't bad either.
Do you run Anti-Virus software? If so, have you added an exception / exclusion rule for Insurgency.exe
Example Location: J:\Steam\steamapps\common\sandstorm
Post up in the beta tech support forums, I should have earlier for my post!
Add a system component breakdown, ping range and maybe your average values shown in the connection debug at the top of the screen in game once you enable it in the options. That could help give people an idea of your issues.