If you get an error "Unable to connect", most of the time it means that the server is unreachable and does not necessarily mean that it is offline.
  1. Verify that the server your trying to connect to is online

  2. Verify your server address to be sure you have the right port and server address.

  3. Verify the address or port field to be sure there are no spaces or unwanted caracters

  4. In some cases firewalls or anti virus can block the communication with the server, click here for more informationa (Anti-Virus and Firewall related issues).