RDP Connection to Windows 10 Pro fails using RDP for Mac client on MBP: error 0x3000008

Trying to connect to a Windows 10 Pro RDP fails using RDP for Mac client, generating error 0x3000008

Used to work fine... RDP client on iPad and iPhone still do work, so the problem must be Catalina 10.15.5 (19F101)

Any idea?

Will try to find the error using Wireshark later....