I have tried Aqara and the Zigbee looses connection to the hub in the freezer … It may work for a week or a month or two and then looses connection. I want something that will stay connected. I placed zigbee repeaters around and it didn’t help. I want something else… any other options out their?
It’s probably the battery which gets discharged quickly and/or the voltage drops significantly… 
How cold is your freezer? 
Yup. I’ve had problems with RF sensors. It’s a chemical reaction, so naturally it slows down at very low temperatures. I don’t think a different technology is going to help much. Lithium batteries generally perform better, if you haven’t tried them already.
I have two large freezers and do the following for monitoring.
Each freezer is on a smart socket so I can check power usage. This helped me identify excessive compressor time caused by a failed cooling fan.
I have door sensors which alert after a minute if the doors are open.
Finally, and to answer your question, I have a Yolink temperature/humidy sensor in each freezer. I tried zigbee and ble sensors but they did not have the range. I had to stand right by the freezers to get any readings from them. The Yolink sensors use standard AAA batteries and last a good year.
Yolink is cloud based and a bit marmite for many people because they have promised a local hub for years. They are allegedly about to release a new hub which has matter and local access but don’t make any decision based on that.
LoRa, which Yolink use, is the only technology I have found to be able to get through the faraday cage that most fridge/freezers are.
~B
I’ve been using a DS18B20 waterproof sensor attached to an ESP8266 for months without issues. The cord goes under the seal to the outside where the ESP lives.
It is very cold around
-17C -20C
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That is a great idea… but my freezer is in the basement and I am in a wheelchair. So I need a solution that I can have my wife use by placing it in the freezer … so i would like a gadget option vs building something option.
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I use Inkbird IBS-TH2 Bluetooth sensors in my freezers. The batteries (2xAAA) last nearly a year.