This is a kind of confusing topic for me to wrap my head around, and I think i have a pretty good handle on what i want to do, but I have no idea on how to go about doing it. 

 

I would like to use a virtual machine on unraid to be the router for my openvpn server.

 

I am very restricted in what I can do network wise because I am behind a school network, but I have a google server running openvpn that has an open ip and ports for ovpn. I also have an unraid server with many spare ethernet ports. I was wondering how I could go about configuring those ethernet ports to assign ips to devices plugged in, but all of that traffic is routed through my ovpn server hosted by Google. I hope that I have my ideas conveyed well. I think my topology would look something like this 

 

Random device -(ethernet)- unraid vm -> google server

Why not install for instance a pfSense VM, then you have a router with built in OpenVPN server,  and client that you connect to your OpneVPN service provider.