A signal above -100dBm should be considered good. A signal between -115 and - 100dBm should be considered mediocre and below 115dBm is considered as weak.
Although LoRaWAN could be received at a signal strength of < -120dBm, there’s another factor which should be taken into account. If there’s a lot of ‘RF noise’, the noise level on the receiver will increase and weak signals will not be received. The amount of noise compared to the signal is referred as SNR (Signal to Noise Ratio).
A SNR above 0 is considered good, while anything below -4 is considered bad.
Low SNR indicates that there is more noise than signal. In that kind of condition your gateway might get the Join_Request from our module and send out the Join_Accept to the module, but the module may never receive it.
The antenna on the module is optimized to work best when mounted at least 10mm from any isolator (plastic / table etc.). Please also make sure that there are no metal objects near or around the antenna.