"Server not found" or "This site cannot be reached" errors means, you are having connection issues to server from your local machine and this can happen due to many reasons including firewall block on server, local DNS issues on your end, network issues, etc. This needs to be debugged live to see exact reason. If you see this happen again, can you contact support department once again. You can either open an helpdesk ticket or contact us on live chat. Link to live chat can be found on below given url.