I found another irritating issue, I will try to explain step by step what is hapening:
Suppose that the router has IP 192.168.5.200 and I have FTP-host in my network at IP 192.168.5.216
The ftp at FTP-host is operating on port 21 (and it has not any option to change the data port 20, the router doesn't have either)
On the router I set Virtual server like in the screen below:
http://www.oscyp.x.pl/virtualserver.jpg
Logically I turned off the built-in FTP-Server on router but then my FTP-host was unreachable.
So it turned out that the built-in ftp-server has to be running but I had to change the built-in ftp-server port, for example 20021.
Everything seems to be ok: wherever I am I can reach my ftp-host simply by connecting to ftp://my_WAN_IP and the router is forwarding ports correctly... until the router restart.
When the router starts again the ftp-host is unreachable even if the every option is like I said above. The solution is that I have to go to USB-Application tab in my router and check again the option to enable built-in ftp-server (despite of the fact that it is already checked!):
http://www.oscyp.x.pl/enableftp.jpg
Only then the ftp-host is working again.
So summing up:
- I have external FTP which is working until router restarts
- after restarting the router the built-in ftp service seems not to be running despite of the fact that it is enabled in the FTP Server tab on the router
- when I chceck the already checked "enable" option in FTP Server tab on the router and save the "changes" everything is working fine again
Question is: What can I do to make the router to start FTP service automatically after restarting?
Sorry for this essay but I wanted to be sure that everything is clear 
Waiting for help 
(Last edited by oscyp on 17 Aug 2008, 11:14)