You receive the error below when attempting to remote desktop (RDP) into a Windows Server running Windows Server 2012, Windows Server 2012 R2 or Windows Server 2016 from a Windows 10 Desktop 
Remote Desktop Connection
An authentication error has occurred.
The function requested is not supported

Remote computer : xxx
This could be due to CredSSP Encryption Oracle Remediation
For more information, see https://go.microsoft.com/fwlink/?linkid=866660
 
Remote Desktop An Authentication Error Has Occurred CredSSP Encryption Oracle Remediation

On Windows 10, click Start and type CMD.
Right click Command Prompt and select Run as Administrator
Paste the following command into the command run window and hit enter to execute.
REG ADD HKLM\Software\Microsoft\Windows\CurrentVersion\Policies\System\CredSSP\Parameters\ /v AllowEncryptionOracle /t REG_DWORD /d 2

CMD FIX An Authentication Error Has Occurred CredSSP Encryption Oracle Remediation

If prompted to overwrite Value AllowEncryptionOracle exists, overwrite(Yes/No)? - Type Y to proceed

Restart your computer and reconnect to the server

The issue occurres after the target server is patched with May 8, 2018—KB4103725 (Monthly Rollup)

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