Ok, I definitely think there is a problem with UEFI PXE network booting on these new PCs.
My setup:
-Secure boot disabled
-I am using toems DHCP proxy.
-DHCP server and TOEMS on the same server
Tests I have tried:
Working fine on these new machines:
USB boot. (winpe and linux images) with the secure boot option disabled from the iso/usb generator page.
PXE with Winpe as boot option.
Not working on these new machines:
PXE with iPXE -> Does not work. It acquires IP from DHCP, TFTP successfully loads iPXE and shows "Configuring (net0 mac)....". It then times out and falls back to IPv6 PXE and reboots. As you have pointed, this will probably be resolved with a new iPXE version which will be included in the next TOEM release
PXE with Syslinux -> Does not work. TFT transfers files correctly but no menu is displayed. It just restarts.
PXE with Grub -> Does not work. The Grub menu loads correctly, but after selecting the "theopenem" menu, the TFT transfers complete successfully on initrd and kernel, but then nothing else happens. Only the message "Please wait while the boot image is transferred...".
Working on an EFIx64 hyper-v machine:
PXE, all boot methods.
I attach some logs and wireshark captures.
logs-efi64-pxe.zip
I have had another issue. Deploying multicast with winpe does not work in many cases. It boots ok, but it somehow closes de session seconds after starting deployment. It has happened using hyper-v test machines as well as physical ones.
Lastly, JFYI: when using winpebuilder, the latest adk version in which you can build x86 and x64 pe images is the v.2004. Later ones can't be used to build x86 images. Web ui want the two images to be available. If not, when the boot method is changed it warns you and seems it does not store the settings correctly.