FTP emtpy response after upload

I did the wordpress upload via filezilla, it worked proper. I then filled in my account information in the wordpress congfig file. When I tried to reconnect to the server, it failed. It says, the server does not send any information. The browser also does not show any content except the error notification. What can I do? What did I miss?

An ftp forum member told me this is a wordpress-thing and should have nothing to do with the ftp-server.