1) Start Arma 3 Alpha and connect to a multiplayer server using the in-game server browser. Having verified that the server works and that Arma can connect to it normally, close Arma.
2) Start Arma with the appropriate -connect and -port parameters for the same server.
(I have tried both entering "arma3.exe -connect=foo -port-bar" manually on the command line, using server details from http://arma3.swec.se, and launching the game by pointing Play withSIX at the same multiplayer server. The results are the same.)
3) Arma waits indefinitely and never joins the server (screenshot of waiting screen attached). I have tried waiting up to 15 minutes.