Option 1 - Configuring the boot order for a virtual machine with on ESXi 6.x / 7.0 or 8.0 using the using the BIOS boot manager:

1. Shut down the virtual machine.

2. Click the virtual machine in the Inventory.

3. Right click Edit Settings.

4. In the Virtual Machine Properties dialog, click the VM Options tab.

5. Under Boot Options, select the check box for Force BIOS setup.

6. Click OK to save the changes.

7. Power on the virtual machine

8. Open a VM console and navigate to the BIOS > Boot section

9. Make your boot order selection and save
   
    

Option 2 - Configuring the boot order for a virtual machine with legacy BIOS using VM advanced options

You can also choose the boot device using the virtual machine advanced options bios.bootOrder and bios.hddOrder. These settings override the boot order that you might have set in the virtual machine's BIOS previously.

The virtual machine's boot order can be set to any virtual NIC ethernetX, where X is the number of the device. For example, ethernet0 or ethernet5. It can also be set to hdd, cdrom, or floppy. If set to cdrom or floppy there are multiple devices, the virtual machine tries them sequentially until it finds one to boot from. If bios.bootOrder is set to hdd, you also need to define bios.hddOrder and set a device (for example, scsi0:3 or ide1:0) to boot from.

To make this change, ensure that the virtual machine is currently in powered off state, then:

1. Right-click the VM in vSphere Client.

2. Select Edit Settings.

3. In the VM Options tab, select Advanced.

4. Next to Configuration Parameters, click on EDIT CONFIGURATION.

5. Select [ADD CONFIGURATION PARAMS] to create the new VM advanced parameters:

bios.bootOrder

ethernet5,ethernet2,hdd,cdrom,floppy

bios.hddOrder

scsi2:2,scsi0:1,ide1:0

In this example, the virtual machine tries to boot with ethernet5. If there is nothing to boot from, try ethernet2. If that fails, try from the disks (hdd) defined in hddOrder, then all CD-ROMs, and finally from all floppies.

$strVMName = "vm-name"
$strBootNICDeviceName = "Network adapter 1"
$strBootHDiskDeviceName = "Hard disk 1"
$viewVM = Get-View -ViewType VirtualMachine -Property Name, Config.Hardware.Device -Filter @{"Name" = "^$strVMName$"}
$intNICDeviceKey = ($viewVM.Config.Hardware.Device | ?{$_.DeviceInfo.Label -eq $strBootNICDeviceName}).Key
$oBootableNIC = New-Object -TypeName VMware.Vim.VirtualMachineBootOptionsBootableEthernetDevice -Property @{"DeviceKey" = $intNICDeviceKey}
$intHDiskDeviceKey = ($viewVM.Config.Hardware.Device | ?{$_.DeviceInfo.Label -eq $strBootHDiskDeviceName}).Key
$oBootableHDisk = New-Object -TypeName VMware.Vim.VirtualMachineBootOptionsBootableDiskDevice -Property @{"DeviceKey" = $intHDiskDeviceKey}
$oBootableCDRom = New-Object -Type VMware.Vim.VirtualMachineBootOptionsBootableCdromDevice
$spec = New-Object VMware.Vim.VirtualMachineConfigSpec -Property @{
    "BootOptions" = New-Object VMware.Vim.VirtualMachineBootOptions -Property @{
        BootOrder = $oBootableNIC, $oBootableCDRom, $oBootableHDisk
    }
}
$viewVM.ReconfigVM_Task($spec)

$vm = Get-VM vm-name; $vm.ExtensionData.Config.BootOptions | Select BootOrder