Hello!
We have moved the discussion here because it was too off-topic in the beta testing thread and it polluted it. That thread is reserved to WireGuard testing in AirVPN and is aimed at finding bugs, malfunctions and so on, if any.
Kind regards
You should always go with the developer's default if you don't know what you're configuring, simple as that. And the default is On, which selects one based on OS and availability of the options. Off is the famous I know what I'm doing switch.