Failed to connect to FTP

I keep getting

Timeout detected. (data connection)
Could not retrieve directory listing.
Error listing directory '/'.

Every time

Can you login and see the directory listing with any other FTP client? If you can, please post log files both from WinSCP and the other client. If you cannot, please talk to your network or server administrator.

See also https://winscp.net/eng/docs/message_timeout_detected