@matthew11 Totally out of scope question for FOG. FOG hasn’t use syslinux for pxe booting in over 10 years. FOG uses iPXE for a pxe boot loader. There are parallels between the two, but they are not the same.
With that said, if you have the default config file for syslinux it might be possible to translate that into iPXE syntax, but I would have to see the changes needed to that file.