See https://winscp.net/eng/docs/rawsettings#ftpforcepasvip2

Hi,
I struggled with file transfer in between WinSCP-client and FileZilla-server with FTPS-protocol with passive mode enabled.

To see what passive FTP means, see here: http://slacksite.com/other/ftp.html#passive. In short it means that FTP(s) server tells the client which TCP-port to use for file transfer. If you can log on to server, but cannot transfer files with FTP or FTPs protocol, this post is for you.

For some reason the FileZilla-server, in some cases, can tell incorrect IP address (=not the same as used to log on) for the passive data transfer. However, you can force WinSCP to use the same address by switching the "Force IP address for passive mode connections"-setting on. The documentation for that is here:
https://winscp.net/eng/docs/ui_login_ftp

If you want to set the switch on for all FTP-sessions, you can set is as default e.g. like this:

• Set the Configuration Storage to winscp.ini and open it (located in the same folder as winscp.exe and winscp.com).
  
• Search for [Sessions\Default%20Settings] -section in winscp.ini. If you don't find it, create it.
  
• Add FtpForcePasvIp=1 line to [Sessions\Default%20Settings] section.
  
• Save and close winscp.ini.