Network Page (Preferences Dialog)

To use active mode with FTP protocol, WinSCP needs to know an IP address, via which the server can reach your machine. If you have a direct connection to the network, WinSCP can ask operating system for the IP address.

But if you are behind NAT router, it would return only the local network address. Then you need to check Use following external IP address and fill your external IP address in the box below. You can find your external IP address using many online services, like whatsmyip.net or Google.

Use When SFTP connection is rejected, knock FTP port to make WinSCP automatically try to detect, if server supports FTP protocol1, when SFTP connection fails. This is to help novice users, who do not realize that WinSCP defaults to the SFTP (contrary to most other file transfer clients).

Read more about Preferences dialog and its other pages.