A required previlige is not held by the client

The remote shutdown option is always safer option to restart the server. This is ideal option when the server is virtual because when you restart the server from the server itself some times server fails to start up.

Syntax: shutdown -r -f -m MachineName

r - restart
f - force
m - machine

But sometimesThe remote shutdown cannot run sometime due to lack of previliges. We can check the following things
Start --> Run gpedit.msc
Go to
Computer Configuration --> Windows Settings--> Security Settings --> Local Policies --> User Rights Assignment
Double Click on "Shut Down the System"

Check if the following groups are listed

Administrators
Backup Operators
Power Users
Users

If any of them are missing, add them.