abortpxe.com is only used for BIOS and not UEFI. See https://learn.microsoft.com/en-us/troubleshoot/mem/configmgr/understand-pxe-boot#downloading-the-boot-files for some additional detail. As noted in this doc, the behavior you are interested in is locally controlled on the device (by the EFI shell) and not determined by ConfigMgr or the PXE server.
Wait 60s UEFI PXE Boot when no deployments assigned
I recently switched to deploying Windows 10 images in UEFI PXE boot mode from MECM (version 2107). In legacy BIOS PXE mode, if there are no deployments assigned, it immediately aborts and then boots the OS. However UEFI PXE Boot hangs for 60 seconds before aborting.
I can see in SMSPXE.log that there are 4 replies, 15 seconds apart, that 'No advertisements are found' before the computer aborts PXE and boots into the OS.
I don't see MECM sending abortpxe.com file so that the computer then starts booting from the hard disk. It seems that the computer waits 60 seconds and since it does not receive a response, then it starts to boot from the hard disk. However, in legacy BIOS PXE mode, it does receive the abortpxe.com file in 1-2 seconds, so it can then boot quickly from the hard drive.
If there are deployments assigned, then in both modes the necessary boot file is received immediately in each case for the OS to be deployed.
Although it can be solved by changing the boot order after OS deployment so that it boots from the hard disk, I am interested in letting them always boot first by PXE.
Any solution would be appreciated. Thanks a lot.