Trying to netboot 20.04 from another OS

Hello - I am trying to do and autoinstall with grub from CentOS 7 to boot up and replace the whole disk with 20.04. So I edit the /etc/grub.d/40_custom to add this entry.

menuentry “Install Ubuntu” --id “ubuntu” {
linux /boot/vmlinuz.ubuntu.20.04 fsck.mode=skip autoinstall ds=nocloud-net;s=https://my_IP/autoinstall/ splash ds=nocloud-net;s=https://MyIP/autoinstall/ ip=dhcp url=
ver-amd64.iso — quiet biosdevname=0 net.ifnames=0
initrd /initrd.ubuntu.20.04

I set the /etc/default/grub to be GRUB_DEFAULT=ubuntu. I ran the grub2-mkconfig -o /boot/grub2/grub.cfg and then rebooted. then at boot - the default is ubuntu - it starts up - but at some point all it prints is /dev/sr0 no medium found.

How do I get it completely boot over the network and replace the current OS.?
My autoinstall files work just fine with the USB thumb drive. Just trying to get the “network” to do it now. What am I missing ?