Hi everyone,
I’m setting up a network of gateways (connected via a mesh network) using ChirpStack as the LoRaWAN Network Server and ChirpStack Gateway OS.
Relay gateways are based on Raspberry Pi Zero 2W + WM1302, while border gateways use Raspberry Pi 4 + WM1302.
I’m encountering a recurring issue where the join process is unreliable — sensors eventually manage to join, but the Join Request is often not received by ChirpStack at all.
Once the devices are joined, uplink/downlink communication works fine (with RX1 delay set to 5 seconds, for example). However, the initial join is flaky, and it seems that Join Request packets are either lost or not properly forwarded to ChirpStack.
What works:
- End devices eventually join (sometimes after multiple attempts).
- Uplink/downlink traffic works correctly once the join succeeds.
- All gateways appear online and connected to ChirpStack (border gateways show up in the classic Gateway Dashboard, relay gateways appear in the Mesh Gateway Dashboard).
Issues:
- Join Request packets often don’t appear at all in ChirpStack’s “Live LoRaWAN Frames”, even though the sensors are transmitting them.
- After several retries, the join typically succeeds.
Troubleshooting steps taken:
- Verified that the border gateways are correctly forwarding packets to ChirpStack (via MQTT). When using only the border gateway with direct uplink enabled, the join works reliably.
- Checked that all gateways and ChirpStack use the same LoRaWAN region and frequency plan (e.g., EU868).
- Confirmed that the mesh link between gateways is active (same keys, spreading factors, and regions).
- Ensured NTP is running on the ChirpStack server and the border gateway (to avoid timestamp issues). The mesh gateways are synchronized manually using the “browser time update” feature.
Questions:
- Could packet loss or timestamp mismatches in the mesh network explain why Join Requests are not processed?
- Are there known issues with using multiple mesh-connected gateways where only some receive Join Requests but fail to forward them correctly?
- Is there a recommended method to debug gateway → ChirpStack packet loss, especially for Join Request packets?
I don’t have enough time today to analyze the full logs, but I should be able to do so tomorrow or next week.
Any insights or suggestions would be greatly appreciated. I can share gateway logs or configuration files if needed.
Thanks!
— Thibaud