Since some users - including me - complain that the Live View often does not work, even though the battery is well charged and the WiFi connection is good, I did a little research and came up with the following solution, which at least works very well for me:
I noticed that if the error occurs, my Doorbell 3 cannot be pinged either. So I suspected that the doorbell would go into a kind of sleep mode under certain circumstances and apparently has problems waking up quickly if it has to be quickly available for Live View or other things.
So I started trying to ping the doorbell at her IP address regularly to keep her awake. Where I previously had a reachability of around 30%, the constant ping increased the reachability to over 95%.
At the moment I am still experimenting with the exact number of pings per unit of time, because I don’t want to ping the doorbell more often than necessary. For example, one ping every 5 to 10 seconds works fine for me.
To automate the whole thing, I wrote a small script that runs permanently (24/7) on a Raspberry Pi 4.
In conclusion, I cannot say whether keeping the Doorbell awake will cost more battery power because it is connected to the power supply of the house bell. However, the app constantly shows 100%, despite permanent pings. But I suspect that keeping the Doorbell awake requires very little or even no battery power.
Perhaps this will bring the expected solution to several of you if the tips from the ring support did not lead to success.
Greetings from Germany