WinSCP默认使用SFTP协议，相反大多数使用FTP协议的其他文件传输客户端。

WinSCP uses SFTP protocol by default, contrary to most other file transfer clients, which use FTP protocol.

因此，当您尝试使用默认的SFTP协议连接到没有SSH / SFTP服务（没有打开端口22），但它有一个FTP服务（打开一个端口21），它表明你可能真的想要使用FTP。

For this reason, when you try to connect using the default SFTP protocol to a server that does not have an SSH/SFTP service (does not have a port 22 open), but it has an FTP service (a port 21 open), it suggests you that you might have actually wanted to use the FTP.

您需要在登录对话框中明确选择FTP协议：

https ：//winscp.net/eng/docs/ui_login

You need to select the FTP protocol explicitly on Login dialog:
https://winscp.net/eng/docs/ui_login

有关详情：

https://winscp.net/eng/docs/message_server_rejected_sftp_listens_for_ftp