Nest thermostat, temp sensor. Horrible

[rockstarbass1]

Bought a temp sensor a week ago, today it suddenly says not connected. Move it to the counter a foot infront of the thermostat. Still won't connect. Removed battery, removed device. Re did the whole set up. Anything I should do besides return the temp sensor? (Throw the thermostat away and buy an ecobee) while I'm at it. 

[Spacerocks1]

Same here. Bought a Learning Thermostat with one sensor last week, configured fine, noticed a couple of days later the sensor was offline. Tried same as above to get it connected. Battery reads 3.07 volts. These sensors should have an indicator on them. Don't know if they only use Bluetooth or if they use that for configuration and then connect to the thermostat with Wi-Fi, but I can't identify it in the device list on my router.

[Spacerocks1]

Solution appeared to be to restart the thermostat. I didn't realize it had a restart function or I would have tried that earlier. The sensor has been working since that restart.