What the error means
The "RPC Server is unavailable" error means that Right Click Tools is having trouble connecting to Remote WMI to run the selected action.
First, check if the Remote Procedure Call (RPC) service is running within Windows Services.
If the service is running and you're still encountering the error, there's most likely an issue with your firewall configuration. Verify that Remote WMI is configured correctly in your environment and not blocked anywhere else on your network.
For further information on investigating potential firewall issues, see Dell's knowledge article: Troubleshooting "RPC Server Unavailable".