Getting very strange behaviour:
All my other apps deployed on my LAN (and even on the same server, also running in docker) work fine, I work in devops for a living, I know how to configure my firewall, that isn't a problem. I know a lot of issues here are random users posting unrelated issues, but this isn't it. With that out of the way, here are some details of my setup:

• Running inside of a docker container, forwarding the UDP port for the server to the host
• If I connect over LAN on a client, it works fine
• If I try to connect using the public IP or DNS name, I get an "unable to connect to world"
• Using the public name/ip, the server DOES receive and reply to single UDP packets, presumably ones that are just pings to show in the client UI
• Using the public name/ip, I can go to this site and it will connect and read the info of the server
• The server itself (not just the container, but the host machine) doesn't receive further packets once the client tries to connect

This makes a whole lot of no sense. It DOES know where the server is, and it DOES connect to get some metadata, but refuses to connect for a game session. 

This is a snippet from the container logs:

bedrock | [INFO] IPv4 supported, port: 19132
bedrock | [INFO] IPv6 not supported
bedrock | [INFO] IPv4 supported, port: 45410
bedrock | [INFO] IPv6 not supported
bedrock | [INFO] Server started.

Not sure what that extra port is, but it shouldn't matter because docker IS NOT forwarding that other port, and local connections work fine despite that.