Hi @Paul_Stewart. I'm using US915, but I suspect you might be on to something re: channel selection. I'm still stuck and can't seem to pinpoint what's causing data to not flow through and I'm not sure where to go from here.
Yesterday, I reviewed the gateway traffic on TTN console and I was able to see JoinReq and JoinAccept messages for my device. However, even though the TTN console indicated that I successfully joined the network, the serial monitor was still showing me the same error message "Join not accepted: denied. Check your coverage, keys, and backend status." I can verify that my keys are correct, and it appears there are no issues with TTN backend, so that leads me to believe it's some type of issue related to coverage.
Additionally, I am trying to send a temperature payloads but only a couple of the messages came through despite the JoinAccept. At one point yesterday, I did receive a couple of temperature payloads, yet the serial monitor still showed that the JoinReq was denied. Now today, I am seemingly back at square one because I cannot consistently get the device to join the network. TTN says my device is online, but FramesUp still reads 0.
I've attached another screenshot that outlines which channels are on/off--I'm guessing these are defined by the TTN library. Is it possible that I'm experiencing unreliability because the gateway and device are attempting to communicate on different channels?