Above text box: "Error listing directory '/'." Inside text box:
"Could not retrieve directory listing
I won't open a connection to 10.0.1.105 (only to 18.104.22.168)".
As I get this error, my laptop with WinSCP has an IP address of 10.0.1.105, and I reach the Internet through a firewall whose external address is 22.214.171.124.
If I click "OK" in the dialog, the transfer window opens without any problem other than that the remote panel only shows a "/" panel. I can transfer files to the remote side (put) without any problem, including into remote directories.
I'm pretty certain this isn't an FTP server problem because I can use the FileZilla 3.0 beta client and it doesn't have any problem.
Somewhere in the FTP remote directory listing process, WinSCP seems to be telling the FTP server to use the local IP address, assuming it's globally reachable when in my case it isn't. I would expect that you could duplicate this problem in any environment with Network Address Translation.