Management network or GUI inaccessible on ESXi host due to physical switch configuration

Products

• VMware vSphere ESXi

Issue/Introduction

• The ESXi host management IP is inaccessible via the Web GUI.
• Testing the ESXi host management network configuration via the DCUI fails when pinging the default gateway and DNS servers.
• The host is unable to resolve external hostnames.
• Network-based SSH access fails.
• ARP cache of the ESXi host shows as incomplete for the gateway MAC address using esxcli network ip neighbor list.

Environment

VMware vSphere ESXi

Cause

The network configuration is either inconsistent with the physical switch port configuration (VLAN mismatch, MTU mismatch), or the physical network path is dropping management traffic.

Resolution

• Check Physical Layer: Verify physical link status and cabling from the ESXi host to the physical switches. Ensure both admin and link status are "Up" by running: esxcli network nic list
• Verify VLAN Traffic Flow: Use the pktcap-uw tool to confirm if the physical switch is sending traffic on the expected VLAN. If no packet is captured, the physical switch is not sending traffic on that VLAN:
  1. Access the ESXi Shell:
     • Open the remote console (KVM/IPMI) to the ESXi host.
     • Press F2 and log in with root credentials.
     • Navigate to Troubleshooting Options > Enable ESXi Shell.
     • Press Alt+F1 to switch to the CLI and log in with root credentials.
  2. Identify the Management Uplink:
     • Run esxtop.
     • Press n to view the network panel.
     • Locate the Management Network port group (typically associated with vmk0) and identify the active TEAM-UPLINK (e.g., vmnic0).
     • Press q to exit esxtop.
  3. Run the packet capture command: pktcap-uw --uplink <vmnic> --vlan <vlan_id> -c 1 
     Note: Replace <vmnic> with the active uplink (e.g., vmnic0) and <vlan_id> with the configured management VLAN.
     
• Validate ARP Status: Run esxcli network ip neighbor list. If the gateway IP shows as (incomplete), the gateway is not responding to ARP requests.
• Engage Networking Team: Provide results of the checks to the physical switch administrator to verify:
  • Switchport VLAN tagging (Access vs. Trunk).
  • Upstream routing and gateway health.

Additional Information

Testing VMkernel network connectivity with the vmkping command
Network connectivity issues on Management Network despite correct IP Hash configuration on the standard virtual switch
ESXi host management network unreachable after physical network adapter replacement