Network NIC (vmnic) is down randomly after ESXi host reboot.

Products

• VMware vSphere ESXi

Issue/Introduction

• When rebooting the ESXi host, the 'Link Status' will show as 'Down' from the vCenter GUI on the ESXi host under -> Networking -> Physical Adapters. 
• After subsequent reboots, the link status 'Down' can alternate between different ports on the same network interface card (NIC). 
• From SSH into the impacted host(s), inputting the command #esxcli network nic list  will display the 'Link Status' of the NIC/vmnic. 
• NIC: Intel(R) Ethernet Controller E810-C icen driver - 1.12.5.0 with firmware 22.5.7 / 23.0.0. 

Environment

ESXi 8.0
vCenter 8.0

Cause

The causes can vary, it was seen some switch software versions. As inherently, the ESXi host logs will not reveal the cause of why the link status is seen as 'down', it will only reveal the subsequent effects. 

Resolution

Contact the switch vendor, where vmnic is connected to, for further investigation. 

Additional Information

Network adapter (vmnic) is down or fails with a Failed Criteria Code
Link state up or down for a vmnic interface on ESXi