The Realtek LAN module is loaded without Realtek module. Result is no eth0. I can resolve by placing the following in init.sh
rmmod r8169 #realtek must be first
modprobe realtek
modprobe r8169
ifconfig wlan0 down #optional, but doing this as only wired connection needed
I'm guessing this is not the best way to fix and probably needs resolving in the initrd.img.
Haven't had time to make sense of how modules are loaded but posting to help others with the same.