We recently ran into this error while migrating an ESXi host from one cluster to another.
The host was re-IP'ed via the admin console and passed the ping gateway, DNS, nslookup tests - which usually indicates smooth sailing.
But upon adding the host to the new cluster this error popped up after a 30 second time out:
Usually this indicates a firewall issue, but a direct VI client connection to the ESXi host succeeded, plus the hostd logs indicated the services were receiving the vCenter connection request and responding with an error after the 30 second time out.
The solution was to use the direct VI client connection to delete all the vestigial (previous cluster) port groups. Once this was complete, adding the host to the new cluster via vCenter succeeded without error.