Hello everyone. I have a very strange issue with my RAK4631 
I have a RAK7258 gateway configured to forward the messages via MQTT to my ChirpStack setup. I have various other LoRaWAN devices that work fine with my setup and I haven’t every experienced any bigger issue with it, but then I started to build a small sensor box based on RAK4631.
I am using a RAK4630-R (RUI3) and configured the LoRaWAN stuff like this:
api.lorawan.nwm.set(RAK_LORAWAN);
api.lorawan.njm.set(RAK_LORA_OTAA);
api.lorawan.band.set(RAK_REGION_EU868);
api.lorawan.deviceClass.set(RAK_LORA_CLASS_A);
api.lorawan.cfm.set(RAK_LORA_NO_ACK);
Then I have a periodic timer to trigger sending a message every minute:
api.system.timer.create(RAK_TIMER_0, send_lorawan_message, RAK_TIMER_PERIODIC);
api.system.timer.start(RAK_TIMER_0, 60 * 1000, NULL);
It builds a CayenneLPP message and sends it:
void send_lorawan_message(void *) {
lpp.reset();
lpp.addTemperature(1, 12.37);
lpp.addRelativeHumidity(2, 56.78);
api.lorawan.send(lpp.getSize(), lpp.getBuffer(), 1);
}
When running my sketch, the first three minutes, everythings works fine. The device sends the messages, my gateway receives them and forwards them via MQTT to ChirpStack. But then… Have a look at this screenshot. It is from ChirpStack:
You do not see the first three messages, but you see some other messages. Have a look for the FCnt. You’ll see a difference of 97:
- 2913 - 2816 = 97
- 2816 - 2719 = 97
- 2719 - 2622 = 97
- 2622 - 2525 = 97
- 2525 - 2428 = 97
- …
And that’s exactly my problem. I only get 1 of 97 messages 
What happens to all the other messages in between?
I already tried to run my sketch with another timer interval and it seems like it is not a timing issue. It seems to be a counter issue
- interval 30s → one message every 48.5 minutes
- interval 60s → one message every 97 minutes
- interval 120s → one message every 194 minutes
I do not plan to send a message every minute or every 5 minutes (maybe every 15 or 30 minutes), but it feels really weird that 96 messages do not show up anywhere I’ve already checked the gateway logs, but couldn’t see anything helpful.
When enabling message confirmation:
api.lorawan.cfm.set(RAL_LORA_ACK);
I see +EVT:SEND_CONFIRMED_FAILED in the logs, for each of the 96 messages that do not reach my gateway. That message shows up ~15 seconds after sending.
The registered send callback (via api.lorawan.registerSendCallback()) receives status 4 which stands for LORAMAC_EVENT_INFO_STATUS_RX2_TIMEOUT from what @beegee said.
If you have any idea on this issue, anything I should try, if you need another screenshot, you want me to test and/or reconfigure something, please tell me! I would really like to understand and fix this issue!
(8 messages)