Web applications written in MVC will not work when it is set to the Web server.
I assume that the problem is not in the firewall or the rights, because when I try to connect from the Web server to destination using WinScp.exe everything works fine.
Localy (on the development workstation) it all works perfectly too.
Debug and Session log attached.
p.s. Almost identical post: https://winscp.net/forum/viewtopic.php?t=15846