I filed a ticket to Customer Support, completely disabling the firewall worked for me. If not take a look at their reply.
The first thing to try is completely disabling any programs that might interfere with the connection, such as firewalls, anti-virus software, Akamai tools, or proxy settings. Do not simply add an exception to your firewall or anti-virus for the game; please disable it entirely for testing purposes. Also try resetting your router if you have one, and making sure you have a reliable and stable internet connection. Then try re-launching the game (as an administrator). If none of that works, please try the following steps to cover all our bases: Make sure your system meets the minimum requirements. Update your OS with all current patches, here: http://windowsupdate.microsoft.com/
Update your DirectX to the latest version, here: http://www.microsoft.com/directx/
Update your drivers to the latest version. (Location dependent on your hardware) Do a complete uninstall of your game. If you have problems with the uninstall, delete the directories, and use something to clean up the registry (http://www.ccleaner.com/) Re-Start your machine. Defrag your hard drive Download the latest client ONLY *FROM THE AERIA SITE* Re-install the game.