In my opinion it’s a typical ‘issue’ with DJI Fly drones that use VSC (Virtual Stick Commands).
VSC is still very different from manual flying !
The number of control signal bars in the top of the screen is just an average, it doesn’t tell anything about complete signal interruptions, especially brief ones.
According to the Air2S specs the FCC transmission range in urban landscapes is approx. 1.5 - 3 km, and the max range is 12 km.
The max CE range is 8 km.
8/12x 1.5 to 3 km = 1 to 2 km
(All theoretical)
Your ‘problem’ starts at a distance of approx. 1.3 km.
Visit the harbor and fly a short mission at the spot for the best possible footage.
Have a look at this topic: