PXE Boot problems with E6320

Good day,

I have a couple of Latitude E6320 laptops around. Some of them are using older revisions of the BIOS, some of them are up to date. 

The problem I have is that my laptops on the A19 revision can't boot into PXE for deployment, whereas laptops with A05/A08 boot just fine. Can someone else confirm that A19 has a problem or suggest a usable alternative solution?

Just to note; I tested one laptop on all 3 revisions mentioned above and it only booted into PXE with A05/A08. As soon as A19 was installed, no more booting.

Anyone else experiencing this? Any help would be appreciated.