It's a web server running in a docker container. It is a database server with a web interface so when it's running entering the IP in the browser a page opens. That is when accessed from within the local network. That makes me think that there is nothing wrong with the server configuration but on the router side.
I'm not really an expert so I might be wrong somewhere here but I could test my assumption by opening the SSH port.
Then if I can't ssh into the PI from outside the network it would mean a problem at the router.
PS: for testing access from outside the local network I use my phone because it is the only device to use mobile network.