For some reason just being default doesn't mean it's the first in the list - so it then changes the boot order to network followed by Boot Manager. I've come up with a powershell script which uses bcdedit to mess with the boot order - first it looks for an entry containing 'IP4', grabs its ID then sets this as the default. Thought this would be easy - surely just set network as the first boot device - only to discover that (on a UEFI booted system) part of Windows setup adds 'Windows Boot Manager' and sets it as the first device in the boot list, no way to stop it. (Bonus points is getting wake-on-lan to work with Win 10 so they'll power themselves up too). The end result I'm after is that all PCs attempt PXE boot when powered up, and then automatically image if there's a task deployment waiting for them. I recently set up System Centre Configuration Manager to take over from MDT for imaging PCs.

Remember the good old days when Windows couldn't change the boot order? Yeah. By Katy Nicholson, posted on 8 June, 2018

Uefi boot manager