Please attach WinSCP logs with and without encryption as well as a verbose FileZilla log.
Hi, I found a bug in WinSCP last version / Win 10 platform. If I use TLS/SSL explicit encryption and upload or delete files on server, connection is closed after about 40 seconds. If I use option without encryption, everything is going fine.
I try multiple servers and also FileZilla - in FileZilla with same settings is also everything fine. So it must be bug in WinSCP.
I can use connection without encryption so it's only up to you if you care about this problem :)