If we click on "Server wechseln" we get an high list of server.
If we try to connect to a server an get "connection failed" and press on "refesh" we get each time an empty list. We have to wait near of 5min until we see up to 5 server and longer wait we get the full list.
So if we press refesh => Wait to 10min(!) until we are able to connect on a good server in a list.