My sensor connected once to my phone (out of the box), then never again. I deleted the app and reinstalled. I removed batteries from the sensor and reinstalled. I won’t clean all bluetooth devices from my phone, or go to another device, as these aren’t reasonable expectations of the manufacturer of a bluetooth device. I wouldn’t keep this device if it doesn’t connect with my phone regularly (iPhone XR). The sensor does show temp and humidity and it has fresh batteries. Any other recommendations, or should I return it?