What to do when controller disconnects during flight
If the downlink (signal from the drone to the remote controller) drops, you’ll lose video on your remote controller (or mobile device) and you’ll continue to be able to control the drone with your remote controller. If you’re not flying within VLOS (you cannot see the drone with your eyes), you can initiate RTH from the remote controller and allow the drone to fly back to the home point.
If the uplink (signal from the remote controller to the drone) also drops, you will no longer be able to control the drone with the remote controller. At that point, the drone will initiate the Failsafe RTH procedure.
From the Air 2S manual:
By default, the drone will return to home (RTH). In DJI Fly, you can customize the “Signal Lost” setting to also make the drone Descend (land at its current location), or Hover (hover in place until the remote controller reconnects or the battery reaches the point where the drone must land).
See the Air 2S manual for additional information and edge cases you should probably be aware of.