There are multiple online tools to check for Open Ports. They can be check if you had done your router's port forwarding correctly and the WAN IP is a public IP that can be access from the general internet.
Key in the IP, and the port you want to check. It should indicate the Port XX is open on YOURIP. If the WAN IP is not public or the router's port forwarding is not configured properly, you'll see that the port is closed. If you are using 4G/5G Sim card, almost all are not assigned Public IP and the telco is using CGNAT to route the traffic. You will not be able to use port forwarding to access the system that's using these SIM Cards.
Some of the fibre broadband are also using CGNAT, and are not assigned public IP. You will not be able to use port forwarding to access the system that's using these fibre broadband.
