I’ve built a gateway (iC880A-SPI + Raspberry Pi), then created a test application and associated a device with the application. The device is an Arduino Nano + AdaFruit RFM9X + sketch using Arduino-lmic library. It transmits the temperature every 60 seconds. Primary reason was the use TTN Mapper to get an idea of coverage.
For the Device, I used the Activation Method ABP, and took the Network Session Key and App Session Key
and pasted them into the Arduino sketch. And it worked. The Gateway Console displays the packets as they arrive, and the Application and Device Consoles also display the packets, and the TTM Mapper sees them and pings them on the map. All good so far.
HOWEVER - after a random amount of time, the Application and Device Consoles stop displaying the packets, even though the Gateway Console still displays them. Therefore they are definitely being received, but something has gone wrong with the Network Session Key and App Session Keys. Create a new pair of keys, and re-upload the sketch to the Nano, and it all works again for a while, till a random period later and it stops. Random = 30-ish mins or more.
I can’t what I might have done wrong. I did wonder if I’d run into the Fair Usage Limits and was being blocked, but searching for that suggested that it wasn’t being strictly enforced.