VMware ESXi host changing from legacy BIOS to UEFI boot causes network issue

Products

• VMware vSphere ESXi

Issue/Introduction

When a working ESXi host that is using legacy BIOS as the boot method changed to UEFI, there could be network issue after the changes. 

After the boot method changes, some vDS may lose their connectivity if there are multiple physical NICs present on the ESXi host. 

On the problem vDS configuration, incorrect uplinks were assigned which were not connected. 

Other ESXi host functionality may or may not be impacted. 

Environment

VMware ESXi 7.x 

VMware ESXi 8.x

Cause

This is not an ESXi issue and this likely is hardware dependent. 

With the boot method changes, the identification of the physical NIC card order may also be changed, therefore, the issue vDS would have wrong uplinks matching to unplugged physical NICs. 

Resolution

To resolve this issue, after making boot method changes, confirm the uplinks used by the vDS to ensure they are matching the uplinks that are active.