in both case you should active node0 as router so you have asus feature (security etc).
then, plug in "node0 wan port" the wire from modem.
if you have bridge mode on modem activate it, else configure a double NAT (search how to, it s not that hard, 192.168.0.xxx for modem and 192.168.1.xxx for node0 and all other)
Then from your node0 ethernet ports go to your nodesX wan in direct if you can, else go to a switch, then to all the nodes Wan port.
Why do you have a switch, the xt8 have a build in 3 port switch, you can deserve all your nodes form node0 ?
Here is what i have done in my father's house :
then, plug in "node0 wan port" the wire from modem.
if you have bridge mode on modem activate it, else configure a double NAT (search how to, it s not that hard, 192.168.0.xxx for modem and 192.168.1.xxx for node0 and all other)
Then from your node0 ethernet ports go to your nodesX wan in direct if you can, else go to a switch, then to all the nodes Wan port.
Why do you have a switch, the xt8 have a build in 3 port switch, you can deserve all your nodes form node0 ?
Here is what i have done in my father's house :