Virtual machines on specific host are inaccessible over the network

Products

• VMware vSphere ESXi

Issue/Introduction

• Virtual machines (VMs) residing on a specific host are experiencing a total loss of network connectivity.
• While other hosts within the same cluster or environment remain functional, VMs on the affected host cannot communicate with the rest of the network.
• This issue is typically observed through failed connectivity tests (such as PING) on those specific virtual machines.

Environment

VMware vCenter Server
VMware vSphere ESXi

Cause

• The issue can be caused by an incorrect mapping between the virtual port group and the physical network adapter (vmnic) on the affected host.
• The active uplink assigned to the virtual switch does not match the physical cabling or the established working configuration used by other hosts in the environment.

Resolution

To restore connectivity, the virtual switch configuration must be updated to use the correct physical adapter:

1. Log in to the VMware Host Client or vCenter Server.

2. On the affected host, navigate to Networking > Virtual switches.

3. Select the affected switch and ensure the required physical adapter (e.g., vmnic0) is added as an uplink.

4. Edit the settings for the specific Port Group:

   • Navigate to Teaming and failover.

   • Move the verified physical adapter to the Active adapters list.

   • Set any invalid or disconnected adapters to Unused or Standby.

5. Save the configuration.

If multiple uplinks are added to virtual switch, in order to determine the adapter mapped to a specific VM's interface, you may use esxtop command (How to find which vmnic a VM is using on ESXi?)

Additional Information

For further troubleshooting of virtual machine network connectivity, please refer to Troubleshooting virtual machine network connection issues.