ProtonVPN but how do I connect between local machines?

So I have two machines and they are both on ProtonVPN which uses OpenVpn and *.ovpn files. So the server is not on my local net but the clients are. What modifications can I make to either my network configuration or the *.ovpn files to exclude 192.168.*.* addresses from the VPN connections? Note that one of the machines has an unused Ethernet port, if we need that.