CaptainSTX
Part of the Furniture
Your ISP's modem-router will then forward your traffic on port 1194 to the Asus router upstairs. And your Asus router will start an OpenVPN connection and you should be able to access your network devices behind the Asus router.
Just one note to clarify your very complete instructions. If using Merlin's firmware then just VPN Server 1 uses Port 1194. VPN Server 2 uses a different subnet.