Here is (simplified) my setup. I need two connections to the world because I do a lot of teaching from home.
Here is the rough setup (just using blocks).
Works fine for me.
The other setup is like this:
This is a setup for teaching in a lab. The switch supplies Power to the Mox via PoE. The two VLANs separate The internet-side of the Mox from the LAN-Side. I made the setup to play with VLANs und to use the PoE.
You basically need a combination of the both setups.
Hope this helps.