Error :  

"The authentication certificate received from the remote computer has expired or is not valid"

Please follow the below steps on server,

Go to run -> gpedit.msc 

  • Local Computer Policy. 
    • Computer Configuration
      • Administrative Templates .
        • Windows Components.
          • Remote Desktop Services  (OR Terminal service).
            • Remote Desktop Session Host (OR Terminal service session host).
              • Security.
                • Require use of specific security layer for remote (RDP) connections - Double click.
                • Enable Then select Layer RDP and then Apply & OK.