I’m using propietary nodes based on Heltec Mini Shell. Some of them are installed in challenging locations which result is very low signal on GW (< -115 dBm) and low and variable SNR (-3 dB to -12 dB). The device works in Class C and uplinks a packet every 10 minutes.
I’m using the heltec lorawan stack and there is a flag for using ADR which is enabled. The join is always performed in SF7 which causes from time to time the device can’t join (I see the join request/join accept packets in the lorawan frames tab of the device but no in the data tab) and the device becomes unreachable for a time (I guess the device keeps rejoining until a success).
The question is that even ADR is enabled, it always works at SF7 and the network server doesn’t instruct the device to lower the SF (the network server sees a device packet every 10 minutes so there are enough data to adjust SF).
Is this behavior correct? Is there something I can adjust?.