First of all, make sure any VPN is disabled.
Now, go to Settings -> Network & Internet -> Advanced Network Settings -> Hardware and Connection Properties and Scroll down until you see your network name. Like Wifi, Ethernet etc. Confirm the details with “Network Name” at the bottom.
Keep a note of the IPv4 Address and the IPv4 Default Gateway.
Now, to grab the credentials of the network panel, you need to go to the back of the internet box.
The Default Gateway is your network admin panel
The IPv4 Address is different on each Computer. This is your Private IP Address
Now, Enter the Default Gateway into your web browser, and Enter the credentials on the back of the network box.
You should be able to look up “{Network Provider} how to open port 25565” for specific help. All major network companies have their way of doing it, and no one is the same. Aka mine is Advanced Settings -> Security -> Port Forwarding -> Create New Rule. In here, you need to enter your IPv4 Address and the port of your Minecraft server. Which is 25565, unless you are opening multiple servers.