While I do not know anything about your bg3 problem I think the reason that you can’t see your own posts might be that your settings are not to display read posts.

Many routers have an option to login to a VPN. Then all traffic that goes over that router to the internet goes over the VPN. Theoretically something like that should also be possible with a Linux server if the server is local. With this setup you shouldn’t need to configure the VPN on your local devices.