@EZY4 You can try using a different iPXE binary like snponly.efi at first. This might work with the A3510. Though on the other hand you can’t be sure if this will work for all your other devices.
Not sure if you can setup a particular DHCP policy based on the MAC address just for those machines to use snponly.efi…
Other than that I suggest you build the iPXE binaries from the latest official code base and see if those work on the A3510. Assuming you have the FOG stuff in /root/fogproject try this:
sudo -i
cd /root/fogproject/utils/FOGiPXE/
./buildipxe.sh
cp ../../packages/tftp/ipxe.efi /tftpboot/
Pay attention to the long output when running ./buildipxe.sh as it might fail for whatever reason. If you feel it ends with an error, post the last 20 lines of the output here and we will have a look.
Make sure ipxe.efi is set in your DHCP again, boot up a machine and pay attention to where the preemble tells you the version number iPXE (g…). That should be different to g4bd0 (default on 1.5.9 installs).