For those of you who do not want to open port forwarding or don’t know how, here is an easy way.
its an easy and free way to set up a vpn. You can only have one vpn on a mobile device (at least apple is that way) so if you have a vpn you are out of luck.
But if you dont, install the app, login with SSO from google or what ever service you use. Install on your Roon Core (it works with most) login with SSO there, and they connect.