b_gray wrote:

However, the default security settings opened my entire server to anyone using sFTP so I have since removed it.

What "security settings" are you referring to? What does it mean "opened my entire server to anyone"?

martin wrote:

Consider using an official Microsoft build of OpenSSH, instead of CopSSH.
https://winscp.net/eng/docs/guide_windows_openssh_server

I installed OpenSSH and it did work correctly with WinSCP. However, the default security settings opened my entire server to anyone using sFTP so I have since removed it. It isn't worth reconfiguring the whole access control structure on my entire folder tree to solve this issue. Thanks anyway,

Benson

It seems like a bug in the server.
FileZilla and Cyberduck work because they do not follow SFTP specification and do not use SSH_FXP_REALPATH request before opening a directory.
Consider using an official Microsoft build of OpenSSH, instead of CopSSH.
https://winscp.net/eng/docs/guide_windows_openssh_server

Several months ago the WinSCP client stopped being able to access any subdirectories on our sFTP server. The FileZilla and Cyberduck clients do not have any issues accessing these subdirectories. WinSCP will let me create a subdirectory and delete it but will not let me access it. The sFTP server is COPSSH version 3.0.0 running on a Windows Server 2016 Standard with all current patches. The client is WinSCP Version 5.11.2 (Build 7781) (OS 10.0.16299 - Windows 10 Pro) using the commander interface as described in the attached log file. Let me know if you need anything else. Thanks,

Benson