Many players are having connection issues, especially from European IPs, which I think, is due to their new defense system, caused by recent DDOS attacks, but that's not so important.

If you are stuck in server selection or can only connect to one server you should proceed as follows:
  1. Restart your router (obvious, but has already helped some people, including me)
  2. Submit a ticket with your IP address (this was suggested by a GM)
  3. You can use a free VPN (Virtual Private Network) in the meantime.
    Virtual private networks change your IP, thus letting you connect again, since your real IP is likely blocked.
    Free VPN reviews:
    VPN Reviews 1 (TomsGuide)
    VPN Reviews 2 (techradar)