Why isn’t port forwarding working?

So on my laptop i am using XAMPP which is running Apache that's listening on 80 and 443 ports. On my router interface which is this: I set up the DMZ like this: Which is my laptop's local IP. Now when I am on the same LAN/WiFi of my router and laptop: Accessing the local IP of my laptop whether DMZ is enabled or not XAMPP's dashboard would show up. Accessing the public IP of my router using my DDNS would also show the XAMPP's dashboard but only when the DMZ is enabled That's the current scenario, the problem is when I am not on the same LAN/WiFi of my router and laptop accessing my DDNS always

Question by Shu Sama on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.