have a situation where at a couple of sites that if you configure the machine for UEFI and attempt to PXE boot it only works the first time. Though if you take the computer to a different VLAN it will again PXE boot one time, but subsequent PXE boots fail. However if you configure the computer for BIOS it can PXE boot all day long. We also then have a site where they can not PXE boot at all if the machine is configured for UEFI. Though we have a number of sites that PXE boot with BIOS or UEFI without any problems whatsoever. The only correlation we have been able to make is that locations using Juniper EX4300 switches have the problem, where sites still using older EX4200 do not have the issue. Though we did find one site today that was experiencing the issue on an EX4200. We even opened an incident with Juniper and they have not been able to provide resolution and our networking team keeps pointing their fingers at the DPs, but all of our DPs are configured identically.
We are on 1602
ip helpers/forwarders DHCP Scope options
Option 66: 10.x.x.x
Option 67: Boot\x64\wdsnbp.com
edit - sorry title should have been "Can only UEFI PXE once, no longer PXE boots afterwards"