Hi,
Below is my custom chirpstack.toml that only modifies the MQTT integration:
[integration]
enabled=["mqtt"]
[integration.mqtt]
server="tcp://$MQTT_BROKER_HOST:1883/"
json=true
# Uplink / events
event_topic="lora/{{dev_eui}}/{{event}}"
# Downlink / commands
command_topic="lora/{{dev_eui}}/{{command}}"
Basically adding custom event_topic and command_topic. When I send the below publish to the MQTT server on the Chirpstack LNS, it basically sends out a warning message as shown below:
Time: 2026-07-08T20:09:09.275917
Topic: lora/24e124126c065524/down
{
"devEui": "24e124126c065524",
"fPort": 2,
"confirmed": true,
"data": "/yj/"
}
Issue point:
PS C:\Users\kvasishta> docker exec chirpstack-docker-chirpstack-1 chirpstack -V
chirpstack 4.18.0
2026-07-08T20:09:09.275508Z WARN chirpstack::integration::mqtt: Parsing command topic returned invalid match count topic=lora/24e124126c065524/down
Basically no downlink is being queued due to the above parsing issue.
