USR5461 Problem FTP > transfer data

The connection to the FTP server is ok but...
When I want to transfer data to an external ftp server trough my
USR5461 from Cute FTP, i have this message:

I have the same problem with all FTP servers!

COMMAND:> STOR test.txt
STATUS:> Connecting FTP data socket 212.78.204.239:55871...
150 Opening BINARY mode data connection for test.txt
ERROR:> Timeout (60000 ms) occurred on sending data to the server.
450 Transfer aborted. Link to file server lost.
ERROR:> File error.

After, the file test.txt is on the server but take only 0bytes

I am in passive mode, when I'm trying to do that without the router or
with an other router its ok!

Can you tell me what's wrong, what can I put in the forwarding ports on
the router?

But the ports change everytime, so I don't know how I can resolve my
problem.

Help me please...