It can also be poor contact between the SIM card and the camera.
Solution: For Reolink Go, press the iron sheet on the SIM card slot so that the SIM card can contact well with the camera.
I had a similar situation.
And even before inserting a SIM card into the slot, wipe the contacts with a cleaning solution (not alcohol).
Good luck to you! It will work out

It can also be poor contact between the SIM card and the camera.
Solution: For Reolink Go, press the iron sheet on the SIM card slot so that the SIM card can contact well with the camera.
I had a similar situation.
And even before inserting a SIM card into the slot, wipe the contacts with a cleaning solution (not alcohol).
Good luck to you! It will work out