Design the networking so internet players can connect

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https://docs.godotengine.org/en/stable/tutorials/networking/high_level_multiplayer.html

[acs]

If you're hosting a server on your own machine and want non-LAN clients to connect to it, you'll probably have to forward the server port on your router. This is required to make your server reachable from the Internet since most residential connections use a NAT. Godot's high-level multiplayer API only uses UDP, so you must forward the port in UDP, not just TCP.