ESXi hosts fail to reconnect automatically after vCenter Server restart

Products

• VMware vCenter Server

Issue/Introduction

After restarting the vCenter Server Appliance (VCSA), all ESXi hosts within a cluster appear as Disconnected. The vCenter does not automatically restore management connectivity to the hosts upon service initialization. This is often accompanied by Failed to resolve address messages in the vCenter logs (vpxd.log).

Environment

• Product: VMware vCenter Server
• Versions: 7.x, 8.x
• Component: Name Resolution / systemd-resolved

Cause

The issue is caused by a failure or significant delay (greater than 120 seconds) in DNS name resolution on the vCenter Server. If the systemd-resolved service is unresponsive or DNS servers do not respond within the expected timeout, vCenter cannot resolve the FQDNs of the ESXi hosts to establish a connection.

Resolution

To restore connectivity, follow these steps:

1. Log in to the vCenter Server Appliance via SSH as a root user.
2. Restart the name resolution service by running the following command:

   systemctl restart systemd-resolved

3. Verify that the vCenter can now resolve hostnames: nslookup <ESXi_Hostname_FQDN>
4. In the vCenter Cluster view, manually reconnect any hosts that remain disconnected:
   • Right-click the Host.
   • Select Connection > Connect.
5. If the host remains disconnected, restart the management agents on the affected ESXi host:

   /etc/init.d/hostd restart
   /etc/init.d/vpxa restart

Additional Information

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