Hello Matt!
We are on the same path it seems, here is the install that finally worked for me after many hours.
put the lan cable in the LEFT port (lan1)
use nano or vim to edit /etc/network/interfaces
auto eth0
iface eth0 inet manual
auto lo
iface lo inet loopback
auto lan1
iface lan1 inet static
address 192.168.1.124
netmask 255.255.255.0
network 192.168.0.0
broadcast 192.168.0.255
gateway 192.168.1.1
dns-nameservers 192.168.1.124 8.8.8.8
pre-up /sbin/ifconfig lan1 up
Like the poster above said the pre-up takes care of getting eth0 up first, the rest is knowing lan1 is the left port! Love the documentation huh?
Edit; I haven’t tried but I assume if you substitute lan1 for wan in the above you can put the cable in the RIGHT lan port and it should work.
Good Luck!