Can't connect to remote Windows 11 PC

I have been using WinSCP for a couple of years to transfer files from my Windows 10 Pro PC in my astronomical observatory to my home PC (Win11 Pro). Yesterday I upgraded the observatory PC to Windows 11 Pro and now WinSCP on the home computer will not connect to the observatory PC -- just times out.

Remoting into the observatory PC shows the FTP service is running and not showing any errors.

Any help would be greatly appreciated.

Can you connect with any other FTP client running on the Windows 11 PC?