nostr:npub126ntw5mnermmj0znhjhgdk8lh2af72sm8qfzq48umdlnhaj9kuns3le9ll may have a better or easier solution for you.

but off of the top of my head, the easiest one would be to use tailscale. it's a private VPN. install this app on your node and set it up on your phone. then add your relay to your nostr profile. i.e. wss://start9-node-name:1234 and then you'd need to launch your tailscale each time you want to connect to your own relay before you launch your nostr client.

the harder way, the way it do it, so i don't have to launch a VPN each time i connect to my node, requires some knowledge of command line and port forwarding on your router. if you want to go that route i can help later. heading to fireworks now.