@fhhowdy This error looks similar to what I might expect when secure boot is enabled. Check the firmware settings to ensure that secure boot is disabled, which will allow the FOG boot manager (iPXE) to load.
Something else to keep in mind is that FOG’s imaging operating system (FOS), is really targeted towards laptop/desktop computers and not servers. Servers often use hardware not commonly found on workstation class computers. I’m not saying it won’t work, we will just need to be mindful if things act abnormally. Machine class isn’t the issue here, because your server is not booting into the boot manager. The problem I mentioned may come when you pick an action from the boot menu.