Tailscale to connect everything. Then in the public server use a reverse proxy (nginx proxy manager or swag) and point it to the tailscale IP of the server you want out.
Been looking for a good offline messenger. Going on a cruise soon. I want to chat with my family. Will have access to the ships WiFi but not internet. Dont want to pay the $100s for a weekend. By biggest hurdle is being on iOS and android. Most apps are not on iOS.
TrackerControl one word.