WIZ550WEB FTP vs. Filezilla / Web browser FTP


I tried the ftp-Server of the 1.1 SW. With a command line ftp client of Linux it is working as expected - after some modification. But with the GUI-based tools such as Filezilla or Firefox with ftp:// it is not working. The reason is both tools (Filezilla & Firefox) open a second ftp command channel, before they start any transfer. Do you have any update for the ftp-server to solve this?