ESXi Host Disconnected and VMs Orphaned due to Duplicate IP Address Conflict

Products

• VMware vSphere ESXi

Issue/Introduction

Issue:

An ESXi host running version 8.0 U3 unexpectedly transitions to a Disconnected state in vCenter Server. While the ESXi Host Client (UI) and hardware management (iLO/iDRAC) remain accessible, the management connection to vCenter is lost. Consequently, Virtual Machines are reported in an Orphaned state.

Symptoms:

• ESXi host status shows "Disconnected" or "Not Responding" in vSphere Client.
• Virtual Machines on the affected host appear as "Orphaned".
• Attempts to reconnect the host may temporarily succeed but fail again shortly after.
• Error logs in /var/log/vobd.log show: [vob.net.vmknic.ip.duplicate] A duplicate IP address was detected.

2026-03-02T00:11:18.359Z In(14) vobd[2098532]:  [netCorrelator] 1220225678545us: [vob.net.vmknic.ip.duplicate] A duplicate IP address was detected for xx.xx.xx.xxx on interface vmk0. The current owner is xx:xx:xx:xx:xx:xx.
2026-03-02T00:11:18.360Z In(14) vobd[2098532]:  [netCorrelator] 1220241767579us: [esx.problem.net.vmknic.ip.duplicate] Duplicate IP address detected for xx.xx.xx.xxx on interface vmk0, current owner being xx:xx:xx:xx:xx:xx.

Environment

VMware vSphere ESXi 8.x

Cause

• The connectivity failure is caused by a Duplicate IP Address on the Management Network. Another device on the physical network is using the same IP address assigned to the ESXi vmk0 interface.
• This results in ARP (Address Resolution Protocol) table instability on the physical switches; network traffic intended for the ESXi host is intermittently routed to the conflicting device (MAC address xx:xx:xx:xx:xx:xx), breaking the vCenter heartbeat and SSL tunnel.

Resolution

To resolve the conflict and restore host stability:

1. Locate the Conflicting Device:

   • Log in to the physical switch connected to the ESXi host.

   • Query the MAC address table for the conflicting MAC address found in the logs (e.g., xx:xx:xx:xx:xx:xx).

   • Identify the physical port where this MAC is being learned to trace the unauthorized device.

2. Verify Conflict via CLI:

   • SSH into a different ESXi host on the same management subnet.

   • Run the arping command to see if a device responds to the problematic IP:

     Bash

      

     arping -I vmk0 -c 3 xx.xx.xx.xxx
     

   • Compare the returned MAC address with the physical MAC of the disconnected host's vmk0.

3. Correct the Network Configuration:

   • Change the IP address of the conflicting device OR re-assign a new, unique static IP to the ESXi host.

   • To change the ESXi IP via command line:

     Bash

      

     esxcfg-vmknic -i <New_Unique_IP> -n <Netmask> "Management Network"