Strugling to get my fog pxe server to work

I have a fog PXE server that I have set up as Ubuntu in a virtual machine, however I do not know what the equivalent of network boot is on open wrt and am struggling finding documentation for the pxe tab in open wrt any help would be appreciated.

Welcome to the community!

You would browse to: Network > DHCP and DNS > PXE/TFTP Settings