[Feature request] net/upnp - Have option for multiple external interfaces

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Is your feature request related to a problem? Please describe.
The UPnP plugin does not have an option for multiple external interfaces. I use IPv4 and IPv6 on multiple gateways so it would be nice to have a separation of options for IPv4 and IPv6 or option to open ports on multiple external interfaces.

Describe the solution you'd like
It would be nice to have a separation of options for interfaces on IPv4 and IPv6 or option to select multiple external interfaces.

Describe alternatives you've considered
N/A

Additional context
N/A

Start by locating the net/upnp plugin and reading how it currently configures the external interface. Determine whether the existing entry point can represent separate IPv4 and IPv6 choices or multiple interfaces. Done means the plugin offers the requested interface selection and applies it correctly for UPnP port mappings.