Network connectivity lost over network extensions during the NE appliance upgrade while DNS server is located in extended network on the cloud side.

Products

• VMware HCX

Issue/Introduction

• When upgrading the HCX Network Extension (NE) appliance, network connectivity over the extended network is lost.
• DNS servers are located on the extended network on the cloud side.
• HCX NE appliance upgrade fails at the configuration stage with the following error: Configuring Appliance HCX-WAN-NE ... GenerateAndPostConfig Failed. Reason: Unknown.
  
• All ESXi hosts appear in a Disconnected state within the vCenter UI.
• HCX is unable to resolve the Fully Qualified Domain Name (FQDN) for vCenter, ESXi hosts, or the HCX Cloud Manager.

Cause

HCX requires active name resolution to be available throughout the appliance update process. If the HCX Manager loses name resolution because the DNS server is unreachable (due to the network extension being down during the upgrade), it cannot complete the configuration, and the upgrade fails.

Resolution

To recover from this state, you must manually define temporary DNS entries in the /etc/hosts files of both the vCenter and HCX Manager to ensure they can resolve required connections. Once resolution is restored, you can perform a redeploy task for the NE appliance.

1. Update vCenter Hosts File Manually

1. Open an SSH session to the vCenter server as root.

2. Edit the /etc/hosts file and add entries for the HCX Manager and every ESXi host in the deployment cluster using the following format:
   
   <IP address> <short name> <fqdn>
   
   Example: 192.168.0.1 example example.com

2. Update HCX Manager Hosts File Manually

1. Open an SSH session to the HCX Manager as admin.

2. Switch to root using the "su -" command.

3. Edit the /etc/hosts file and add entries for every ESXi host, the HCX Cloud Manager, and vCenter:
   
   <IP address> <short name> <fqdn>
   
   Example: 192.168.0.1 example example.com

3. Verify and Redeploy

1. Log in to the HCX Manager (port 9443) via a web browser.

2. Confirm the network connection to vCenter shows a green circle (connected).

3. Perform a redeploy of the NE appliance that previously failed. Ensure the "force" option is selected.

4. Once the redeployment completes, network connectivity over the extended network will be restored.

Additional Information

Upgrade HCX