@johnpoz

My configuration in:
System / Advanced / Firewall & NAT / Network Address Translation / NAT Reflection mode for port forwards
is set to "NAT + Proxy"
and when I set to "Pure NAT", I can list the ftp content from LAN

So, it seems a solution, as it works. But as I have set Squid Proxy, perhaps it's not a good idea to set "Pure NAT"?
Otherwise, can I create a rule which simulate the "Pure NAT" setup with "NAT + Proxy"?