We have a couple of these HP 260 G1 computers on test.
I have enabled legacy support in the BIOS, set network book to be the default and rebooted. It picks up the network boot and starts the iPXE process and gets as far as:
ipxe 1.0.0+ (3a02) -- Open Source Network Boot Firmware --
features : NFS FTP <etc>
Configuring (net0 <mac addres> ) ......
and then boots into windows rather than the menu.
Any ideas where to start looking? Google didn’t show me anything with what I searched for…