Aeon labs 5gen multi sensor wrong temperature

[Plantje]

I bought 3 Aeotec DSB05 Multisensor devices. If I look at the temperature it displays -17.6 degrees Celsius. Whereas my Toon thermostat and Fibaro smoke sensor in the same room display 22.4 resp 22.1. I can understand a 0.3 difference, but -17.6 degrees Celsius seems way off.

Every once in a while it peaks to about 13 degrees Celsius. Still not accurate. In my daughters bed room I have a second sensor that is stuck on -17.6 as well and peaks to +16.something every once in a while. Still not accurate as the first floor hallway (really next to it) has 23.3 degrees Celsius.

Is there some sort of setting that I need to apply to make this work?