Cannot connect over FTPS

I cannot connect to a particular 4096-bit FTPS server with WinSCP.
Connection attempts complete successfully in FileZilla.

After some inactivity on "Connecting to host...", WinSCP tells me the server has closed the connection.

Log file is here: https://pastebin.com/a0EEBjfx

The log file is for SFTP, not for FTPS session. What protol do you want to use? Can you post a log file from Filezilla?