The 3rd gen automatically chooses the best connection type in the app, based on your proximity to the lock (Bluetooth or WiFi).
Auto-lock/unlock then triggers based on the geo-fence and the best available connection type. I’m sure your Wi-Fi and Bluetooth strength will determine how reliable this works. When you first setup the lock and Connect, it tells you if the signal is strong enough. You can also check the signal strength for both any time in the app.
I mainly chose August because you can still use a key regardless, but also because it works with HomeKit.