AirVPN port forwarding support

[mlsh0]

URL to the Wiki page

https://github.com/qdm12/gluetun-wiki/blob/main/setup/providers/airvpn.md

What's misleading?

Wiki states that port forwarding is avaible for AirVPN however gluetun logs show someting different
ERROR VPN settings: provider settings: port forwarding: port forwarding cannot be enabled: value is not one of the possible choices: airvpn must be one of perfect privacy, private internet access, privatevpn or protonvpn

[github-actions]

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[jinja2ninja]

I think this may just be a case of inaccurate documentation. Can you do the test described here? What works for me is following the airvpn setup on the page you linked, which doesn't involve using the VPN_PORT_FORWARDING=on environment variable. If I do add the environment variable to my container, I get the same issue you're describing.

This is how I have mine setup on version v3.39.1:

    environment:
      - VPN_SERVICE_PROVIDER=airvpn
      - VPN_TYPE=wireguard
      - WIREGUARD_PRIVATE_KEY=<private key>
      - WIREGUARD_PRESHARED_KEY=<preshared key>
      - WIREGUARD_ADDRESSES=<ip address>
      - SERVER_NAMES=<server name>
      - FIREWALL_VPN_INPUT_PORTS=<my airvpn port>