Have you tried the Canyouseeme website to see if the port is showing as open? Do this from your own network.
If your public IP address ends in 79.71 (seen on my website), then the Microsoft PortQuery utility says that port 8150 is not listening. Its not showing as filtered, which would normally happen if the port was not mapped.
If that is your IP address, then I would say the issue is within the camera settings and not the home hub.
Just to add, I can see a wide range of ports from 8150 to 8350, that are assigned but not listening.
Is it possible to give the camera a static address on the camera itself? If it is try giving it an address of 192.168.1.20 and forward the port to that address rather than letting the hub assign an address with DHCP.
It sound like the normal issue with the HH6 and the earlier home hubs, when the hub assigns an address via DHCP, just as @licquorice has pointed out.
This issue was mentioned on my website, and seems to be more of a problem on the HH6a version.
I do not use a home hub, the example pages were from a remote HH6 which I used to manage.