Yesterday I enabled the Proxy option in the Qt client and left it active unintentionally. Today I started the client and it didn't connect, opened the log and saw a bunch of "socket select error 10022" messages. It came to my mind I had played with the Proxy option, disabled and now the client connects just fine.
What I want to say is, that we need a better user feedback here. A client that can't connect needs to tell the user why or at least give some options the user could try to fix the connection-problems.