I took a bit time to write down some copy-pastable steps for troubleshooting. If you have more tips, I can add. But here those tips are! @Mengdi are you able to create a pinned post that could be updated with tips on how to recover functionality for different products? I’m not sure how well that works, but at least it might be into right direction.
Things to try with at least Eufycam 2C and Homebase2 in case of problems or after firmware update. These can be tested in order. I’ve tried everything from 1-6. After the latest firmware update I did 5abc and it started working. The 6-7 are “last resort” steps.
Reboot the HB2 (via app or power key)
Disable and re-enable camera (Camera On in app)
Disable and re-enable motion detection in app (motion detection)
Set motion detection to 1 and back to normal in app (motion detection)
5a. Reboot HB2
5b. Press camera physical sync button until getting audiovisual signal (beep/red light, inaccessible from app)
5c. wait for a while and press a little while and get blue light in camera (verify it comes back in app. If it doesn’t you need to re-add the device)
try removing cameras from HB2 and reconnecting them
Try removing camera from HB2 and reset HB2. Setup everything from beginning.