I have a Windows Server with RRAS with NAT but passive FTP doesn't work

Question

I have a Windows Server 2019. RRAS with VPN and NAT installed and configured.

I can access any FTP site from the server.

But using passive FTP from any client doesn't work. I get a timeout.

Access to any web site works.

Any idea?

PS.1: I already deactivated the RRAS and configured it again, but no avail.

PS.2: Disabling the Firewall doesn't help either. For testing purpose no other firewall except the Windows Firewall ist running.

PS.3: From the RRAS server I can use any FTP connection I want. So firewall isn't an issue here.

Answer 1

The problem wan an enabled FTP Proxy on the RRAS server.

I need to disable this and it works. This is done with the following command:

netsh routing ip nat delete ftp

And here is the description of this command - "Disables the FTP proxy on the NAT server." http://technet.microsoft.com/en-us/library/cc754535(v=ws.10).aspx#BKMK_106

In fact I have no clue how this proxy was enabled...