Sounds like you are making great progress, congrats!
It sounds to me like everything is working as it should now, so we need to either:
reset your expectations and correct your assumptions, or
have you communicate why you think something should work a certain way or what your goals are.
Putting your first and third posts together, it sounds like you expect to see the WebGUI on multiple ports. Can you explain why you would want that? I'm not going to say you couldn't engineer that, but I'm going to challenge your thinking here. Let's assume your machine has a local network static IP of 10.77.77.42; you access the WebGUI with http://10.77.77.42:8082 right? Why do you need additional access on port 27586? Are you trying to admin qBittorrent from outside your network? You haven't stated that before which is why I ask.
Many users are uncomfortable exposing their WebGUI to the world, so you need to be clear that this is your desire (and secure it with https before doing so!). How many ports do you have forwarded from AirVPN? Are ports 8082 and 27586 in pool #2 (saving pool #1 ports for P2P users is the goal here)? Your line "FIREWALL_VPN_INPUT_PORTS=8082,27586,27587" isn't going to work unless all three of those ports are forwarded from AirVPN. I believe the most common use case is to only forward the torrenting port from pool #1 (27587) keeping the WebGUI port just for local network use.
Lets check your devices to ensure they are not an issue. When you go to the devices screen have you set up a device? Then in the ports screen is that device linked to the port (in the dropdown)? And when making your config file did you select that device? When working correctly, the sessions screen should list your device at the top of the card when connected.