Why does the Zyxel USG 100 not allow connecting from an external network to an FTP server?

Question

FTP

Greetings colleagues.
Tell. There is a Zyxel USG 100 with extreme firmware and an FTP server (windows server 2008 + IIS)
Before that, there was a Zyxel zywall 35 with a simple port forwading on board to port 21 of the local FTP server and a rule in the firewall from external to local FTP.
Put more seriously Zyxel. Set up VPN, Firewall on it. Everything seems to be working, but the employees cannot connect from external to the FTP server.
Connect to it via WinSCP.
The error is d.pr/i/8zH2
Google said that a possible solution is to remove the passive mode. Removed, some helped some and see this error.
Settings Zyxel USG 100
NAT d.pr/i/YlbU
Firewall d.pr/i/hZcq
ALGd.pr/i/HYtS
FileZilla connection log pastebin.com/AQVvpNGS
As I understand it, the problem is getting the list of directories. Tell me where and in what direction to dig?

Answer 1

Solved this problem.
The problem was in the Windows Server 2008 FTP server itself.
I had an external IP in d.pr/i/HjIX , on the advice of Zyxel TP I changed it to a local one and everything worked.

Answer 2

Forward the twentieth port