VMware ESXi host shows disconnected

Symptom:

The host and VMs in a vcenter server appears to be disconnected.

Issue:

The host and its corresponding vms could appear as disconnected due to issue with any of the following services.

• vpxa - a service which runs in the esxi host. This service communicates with vcenter server.
• hostd - core service which runs in the esxi host
• vpxd - a service which runs in the vcenter server which communicates with the vpxa

Resolution:

1. Try to ping the ESXi host. This ensures that the host is reachable
2. Ensure you can login to the VMs remotely. This ensures that VMs in the host are working fine.
3. Try to login to the ESXi host using vsphere client. This ensures that the hostd services are running perfectly. If this step fails, restart the hostd service using putty.
4. If the above three steps worked fine for you, the issue would be with the vpxa or vpxd service. In that case, first try to restart the vpxa service in the host and if that didnot resolve the issue, try restarting vcenter server service of the vcenter.