BUG: FTP running in PASV mode

Hi everybody!
I have installed my ASUS WL-550gE for several days now... Last week I wanted to upload some pictures and a new HTML file to my webhoster's ftp-server. But if I was connecting to the ftp in PASV mode all uploads abort after transfering about 500-1000 bytes...
As I searched in this forum, I found this in your FAQ: "21. Unable to transfer any data to/from built-in ftp server when client is running in passive mode and server port is not 21. Affected versions: all stock firmwares"

But the server I'm connecting to is not built-in even not in my LAN and is running on port 21, but in PASV mode... :)
I can connect the FTP server of my webhoster also in active mode, but other servers require a connection and transfer in PASV mode. Is there a possibility to forward that bug to ASUS in any way? Because I've written 2 support tickets, but with no respond. Is there any workaround?

EDIT:
I'm using firmware v1.9.6.2!

Hope you can help me out!
Thanx.

Regards
Mike