vCenter Server Connectivity Loss via Specific Physical Uplink

Products

• VMware vCenter Server

Issue/Introduction

vCenter Server experiences total loss of network connectivity. Disconnecting and reconnecting the network adapter may temporarily restore access, but the issue recurs. This typically manifests as:

• Inability to access the vSphere Client.
• Loss of ICMP ping response from the vCenter IP.
• "No route to host" or timeout errors when attempting SSH or UI connections.

Environment

VMware vCenter Server

Cause

The issue is caused by a communication failure on a specific physical network adapter (vmnic) assigned to the Distributed Virtual Switch. While the DVS may have multiple uplinks, if the teaming policy hashes traffic to a faulty physical NIC or a misconfigured upstream switch port, the vCenter will lose its path to the network.

Resolution

To restore stable connectivity, you must isolate the faulty uplink and remove it from the active teaming configuration.

1. Isolate the faulty uplink: Create a test port group on the same DVS and VLAN.

• Assign a test VM (or the vCenter) to this port group.
• Modify the Teaming and Failover settings to use only one uplink at a time until the specific failing vmnic is identified.

2. Remove failing Uplink

• Log in to the vSphere Client.
• Navigate to Networking > Distributed Virtual Switch. Right-click the affected Port Group (where vCenter resides) and select Edit Settings.
• Go to Teaming and Failover. Locate the identified faulty uplink and move it to the Unused uplinks section.
• Click OK

3. Physical Inspection: Engage your hardware or networking team to inspect the physical NIC, cabling, and the configuration of the corresponding physical switch port.

Additional Information

This is considered a workaround to restore vCenter availability. To maintain high availability and redundancy, the underlying physical path for the disabled vmnic must be repaired and then re-added to the active uplinks.

Reference KB- vCenter network connectivity lost - Recover vCenter network when connected to a Distributed Switch