EL8 fails to boot with the default iPXE template due to the ip= parameter. This is not properly formatted. Per the documentation at https://fedoraproject.org/wiki/Dracut/Options#Network it should be formatted similar to:

ip=${netX/ip}::${netX/gateway}:${netX/netmask}:<%= @host.name >:eth0:none nameserver=${dns} ifname=eth0:<= @host.mac %>