After a recent Eufy Android App update, viewing events and live video from my S340 camera would freeze, stutter, generally be unusable.
Eufy support chats and emails were not helpful. Eventually I identified one simple change that made a difference.
On my router in the wireless setup for the 2.4Ghz SSID my camera is connected to, I changed channel bandwidth from 20/40 mhz to 20 mhz. This made a significant difference. Now have smooth live video and playback of recorded events.
I had never bothered to change this setting previously since it did not cause any known issues. However, the result of this change is no overlapping channels, less interference, and a more stable Wi-Fi connection for the camera. The only other devices I have on this SSID are smart plugs which are unaffected by the change.
While there may be reasons in some isolated environments to use the wider 40 mhz, apparently the trade off in interference is not worth it for most of us.
I don’t know what happened with the Eufy app update to trigger the original issue, but hope this info may help others who experience the same performance problems.