Trying to add Hyper-V System Center or Failover Cluster or Host: The RPC server is unavailable. (Exception from HRESULT: 0x800706BA)

Any option I tried gives me this error.
I check RPC, WMI, TCP are enabled. FW and AV are off. All on host.
My user is administrator on Cluster and VM host.
I can't add a target to backup!
As I have auto balancing resources on Hyper-V Cluster the host VM change Nodes on a weekly basis and that makes the backup job loses its reference.
What can I do? HELP!

The machine does not appear to be a valid Hyper-V host.  Please check that the Hyper-V role has been correctly installed on it. >> This VM is a host on the Cluster!