I found a work around for people who are only getting "could not connect" messages and never acctually launching the game,

Make a shortcut to the client in your AOS folder, then right click and go to properties and put "C:\Program Files\Ace of Spades\client.exe" -aos://123123123

Replace the numbers with the server numbers that you are trying to join, worked well for me if you're having troubles with browsers not recognizing the aos protocol.