This seems to be unrelated to an actual login issue.
If it says it can’t reach the server it usually means that the connection has been somehow interrupted. The software retries for 30 seconds and afterwards it gives you this error. When you first start it takes you straight into the Tutorial so the connection problems are ignored, but they are visible afterwards – probably this is the reason you didn’t see it for the first time. Try enabling the software on your firewall/router, and make sure it has access to the internet.