Every time I try connect to a server I get in start to change my weapons then I get disconnected with that error message. I have NO idea why.

I thought it might be my router as it has problems with steam and its servers and usually resets my network but its not that often and I can deal with it on TF2. However this is happening every time and its not resetting the network so I have no idea whats causing it.

And yes Brink is allowed through my firewall.

Anyone have any ideas?

Exactly the same error for me. I've opened the ports (and verified they are open), with no luck. My connection is stable and plays games fine, except for this one.

A friend in the server I tried to join said he seen a "Could not authenticate user" error come up on the server when I tried to join. I think these errors are linked.

This is a steam issue. a common one for a lot of steam games

post it on their forums

BC2 had similar issues and the main cause was buggy DSL routers, try disabling uPnP on your router and see if that helps.

I figured this was the problem, and disabling uPNP was the fix for me on BC2 as well. Unfortunately it doesn't work for Brink, and the other fix for BC2 (increasing the TCP Timeout) isn't possible on the routers with this issue. I have a new router in the post on the way to me, so hopefully that'll work.

My new router arrived and it solved this issue immediately. This is an issue with the Thomson O2/BT routers.