Sometimes when using Filezilla FTP Client to connect a FTP location you may experience following error:
Server does not support non-ASCII characters.
425 Can't open data connection.
Failed to retrieve directory listing
To fix this error you will probably need to visit Site Manager of Filezilla Client application and for the FTP site in question, click to Transfer Settings Tab and change Transfer mode to Active. Click OK and try to connect again.
Upon applying new settings connection should work again.