Hi @langesmalle
I did not manage to find the root reason of why the discovery image stopped working.
I tried, as suggested from @lzap , to use UEFI http boot, but without success.
We have many HP DL380 Gen9 e Gen10. I tried to use the “Boot from URL” feature, by using an URL like http://IP_SMART_PROXY/httpboot/grub2/grubx64.efi.
This returns a grub> terminal with
Minimal BASH-like line editing is supported. For the first word, TAB lists possible command completions. Anywhere else TAB lists possible device or file completions.
httpboot was enabled on both master and smart-proxy. I had to redirect with a firewall rule port 8000 to 80.
As a reference, I followed (and found interesting) the following guides/tutorial:
https://lzap.fedorapeople.org/foreman-doc-ng/doc-Provisioning_Guide/index-foreman.html
My workaround (for now 
) was to use the “Create Host” option in foreman, manually type all the MAC addresses of the server, configure OS/partitioning and then directly run the provisioning. But this is a bit annoying, since the discovery saves a lot of time / manual work.
@lzap what do you suggest to try to fix httpboot?