Occasionally it does happen that the user is not able to Reboot or Shutdown the Server. Specifically this seems to happen on Windows 10 since the Creators Update.
Search for the "Shut down the system" policy
Default the group Administrators has the Right to Shutdown or Reboot the system. However, since Windows 10, a member of the group Administrators does occasionally not have Reboot / Shutdown in its StartMenu. This could be an intended feature: the Administrator needs to logoff first, and use the Reboot / Shutdown function as it is available on the Windows 10 Logon Screen. Or it could be a bug....
The following work-around works usually OK for us:
The next time the "user" does logon to the Server, the user is able to Shutdown / Reboot the Server.
Example for "testuser" with AADS Start Menu
Example for "testuser" with Windows 10 Start Tile Menu:
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