Roon requires all connected devices to be on the same IP subnet, which means no remote connections by design, only local LAN connections. That said, a number of users apparently have been able to make remote connections work with VPNs and other advanced networking configurations, but this is out of scope of the design of Roon for now.
As others gave said, it’s officially completely unsupported by Roon.
But if you have a fairly decent understanding of networking, routers and VPNs you can get it to work.
You’ll need to be running a VPN like Wireguard to connect back to the Core. But you’ll also need to use an additional UDP proxy like udp-proxy-2020 to send UDP broadcast packets over different subnets so that your remote clients / endpoints can be discovered by your Core.
Have a read of the following, or search for VPN.
But unless it all makes clear technical sense to you and/or you have exactly the same setup / hardware as one of the guides below, it’s probably best to skip trying to get it to work. Getting Roon to work over a VPN is very much in the ‘tinkering’ category for now.
If you don’t understand what your doing there is a real chance you could brick your router or cause yourself no end of headaches. So tread carefully.