When starting the FRS's Remote Admin Console, you may receive the error message "Unable to perform RPC call. Server is not available." when the Server Manager service is running under the user account.
There are several possible causes for this issue, and one of them may be due to the user account that runs the Server Manager's service doesn't have full permission.
To resolve the issue, first, we need to check if the Server Manager can start with the Local System account or not.
Open Windows Services and set the Server Manager service to run under the Local System account.
Then start the Remote Admin Console.
If the Remote Admin Console can start without the error under the Local System account, then that means the user account that runs the Server Manager service doesn't have full permission on the current machine.
Check the user account's permission and give it full permission.