I was having the same issue as others describe. Used both methods, setting up the server through Steam favourites and using the direct link and I would always get insta disconnected before the password window popped up. Server status was online and ready. Tried restarting with no joy. The solution for me was to force a server update. I was able to log in immediately after this. So give an update a go if you're having the same issue by selecting Yes, run update on the Server update radial on the control panel.