If you are wanting an easy way to connect your devices like they are on the same LAN even know that they are on different LAN’s, or you are away from home.
Then look to Tailscale.
I use it myself and I can easy connect to my TVheadend server (running on Odroid C4 on Coreelec) and NAS both running Tailscale from my laptop also running Tailscale also - I just use the IP addr given to my device from Tailscale and it just works.
I can even share a device with a friend (if he is using tailscale).
You first need to add entware and from there you can install Tailscale.
I don’t use Tailscale but I have no problem using my own VPN networks (Main: WireGuard and Auxiliary: ZeroTier) and turning my CoreELEC devices into network bridges to access internal subnets 192.168.0.0/16. For this it is enough to include the following code in /storage/.config/autostart.sh