Getting error in foreman for foreman discovery image boot using pxe

Please attach log files from the Discovery instance, the proxy server, and the Foreman server.

This is a problem with DNS, name or service not known.

it is searching for grub2/grub-mac_adress file which is not present under grub2, how can I generate it for ubuntu:20.04

To determine what files are used to build your host, you have to check on that host’s configured templates.