Need help trying to host a game server, port forwarding, IP fixed/dynamic

[Tim20]

I am trying to host a server for a game. I have forwarded the relevant port (2456) in the smart hub set up but whatever I do it won't open. I have tried checking the port at "http://www.ipv6scanner.com/cgi-bin/main.py" and it shows it as "Filtered". My friend thinks the problem might be that my external IP address is not fixed. I don't know how to check or change that. Does anyone have any ideas? 

[licquorice]

If you are attempting to connect to your external IP address directly, it doesn't matter if it is fixed or not. Your IP address will be dynamic with BT residential so to overcome having to inform people wishing to connect what it is every time it changes, you can use a Dynamic DNS service to track the IP address.

The port will only show as open when the application using the port is running.

Have you disabled UPnP as that might cause a conflict if you have manually forwarded a port.

What does https://www.grc.com/x/ne.dll?bh0bkyd2

show for the port?

[Tim20]

I tried disabling UPnP, it made no difference.

Your link shows the port as "Stealth" and "altav-remmgt"

[licquorice]

Are you sure you have forwarded the port to the correct device/local IP address?It is best to allocate a static IP address on the device (PC) itself rather than using address reservation on the hub and then forward to the IP address rather than device name. Is the application running?

[Tim20]

I have checked all of these things and the server application is running. I set the IPv4 on the pc so that should be static. Still the same problem of the port not opening.