If your PC is receiving Activation issue with error 0x800706BA, then there is something wrong with the Computer's RPC server.

If you do not know, this RPC server issue means that your Windows computer is having a problem with communicating with other devices.

To resolve this, you can try multiple solutions:

1] On the KMS host, make sure the firewall exception settings are configured properly on the KMS host computer.
2] DNS SRV records are stale. SRV records are created to the servers can be accessed quickly. Make sure SRV records point to a valid KMS host.
3] If nothing else works, make sure to troubleshoot network.