Something we've been doing for several years now is set the BIOS to only
PXE after receiving a WOL. (The last 6 years of Dell kit does this with
the latest BIOS firmware).
This gives faster startup times every boot, makes it a little more
difficult for someone to pxe boot a lab machine from a clonezilla laptop
and crossover cable etc.

We create schedules and scripts for sending WOL for re-imaging.
We have a web page where we can set machines/labs to re-image, by
sending them a WOL.
Si

>>> On 16/05/2018 at 10:10, in 
> message
<[log in to unmask]>, "Nelson, 
> Lisa"
<[log in to unmask]> wrote:
 ‑‑‑‑‑Original Message‑‑‑‑‑
> > From: Support issues for windows in UK HE & FE [mailto:WINDOWS‑
> > [log in to unmask]] On Behalf Of Skender Osmani
> > Sent: Monday, May 14, 2018 5:08 PM
> > To: WINDOWS‑[log in to unmask] 
> > Subject: Switch from Legacy BIOS to UEFI
> > 
> > Just wanted to get a feel as to how many of you have moved from
using 
> legacy
> > BIOS to UEFI. Currently we are still configuring new PCs to use
legacy BIOS
> > and are working to get our backend infrastructure ready to support
UEFI
> > network booting. We have number of dual boot machines (Windows and
Linux)
> > and use syslinux/pxelinux to provide a boot menu for students to
choose
> > which OS to boot. Syslinux/pxelinux does not provide full support
for UEFI
> > network boot and we are looking at iPXE as an alternative to do the
above.
> 
> To expand on what my colleague Mike said yesterday, we experimented
with 
> UEFI about two years ago, got as far as a pilot and then had to roll
it back. 
> Our situation is likely different from practically anyone else's, in
that we 
> leave PXE enabled on our student walk‑up machines forever. We do
automatic 
> overnight reimaging once every four weeks to keep the machines clean.
We also 
> have made the information widely available about how to start
reimaging on a 
> machine, so that students can initiate reimaging and fix software
problems 
> even if it's 2:00 AM. This has been very useful. So in our
environment, any 
> changeover to UEFI has to be able to handle PXE being left enabled 
> permanently, not just used for initial installation. All our problems
stem 
> from this.
> 
> Below is an extract from a report I wrote at the time, after we had 
> abandoned it:
> 
> o	A subtle change in the wording of the PXE‑boot invitation on
UEFI PXE caused 
> human problems. The legacy wording was "Press F12 for network service
boot"; 
> on UEFI this changed to "Press ENTER for network boot service". This
wording 
> apparently makes people feel that they must press Enter, or they will
not 
> have network. Stations were constantly being reimaged. Many
experiments with 
> modifying this wording (which required modifying an executable with a
hex 
> editor) and other attempted psychological interventions yielded no 
> improvement.
> 
> o	It has always been possible to press Escape as soon as the
attempt to find 
> a PXE server began. Doing so allowed skipping several seconds of PXE

> activity, and so was a sensible thing to do when not wishing to
reimage a 
> computer. Students have clearly learned this and use it.
Unfortunately, if 
> you Escape during the attempt to locate a PXE server in UEFI PXE,
Windows 10 
> comes up with no network and never regains it! This only reinforced
the idea 
> that pressing Enter was necessary to get network.
> 
> o	It has also always been harmless to press Escape from the
offered menu of 
> PXE choices, should you decide that you don't want to reimage after
all. 
> Doing so just caused the BIOS to move on to the next boot source,
i.e. the 
> hard disk, and boot Windows normally. Under UEFI PXE, pressing Escape
at this 
> point instead displayed a pointless full‑screen cryptic error with a
hex 
> number, with instructions to press either Escape a second time (to

reboot) or 
> Enter (to continue with the boot order). Even better, on the HP 800
G1, these 
> instructions fall off the bottom of the screen and are not visible.
> 
> o	The final nail came when we found that the promised
near‑instant‑boot for 
> Windows 10 with UEFI did not materialize. To get this, all legacy
support 
> must be disabled, and we have no hardware types ‑‑ not even the very
latest ‑‑ 
> which support this. Additionally, you must disable PXE!
> 
> Thanks,
> Lisa. 
> ‑‑ 
> Lisa Nelson
> Computing Services Department
> e‑mail: [log in to unmask] 

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