Using external Broker with Chirpstack

Hello,

we are not using mosquitto on the same server as chirpstack for many reasons. In our installation we are using a mqtt-broker running on another server, so I configured gateway-bridge for mqtt-pub and chirpstack for mqtt-sub to the external broker.
Everything works fine until I tried to upgrade from version 4.6.0 to version 4.9.0 of chirpstack.
Since this version, chirpstack seems to subscribe topic “$share/chirpstack/eu868/gateway/+/event/+” instead of “eu868/gateway/+/event/+” as it was before.
Because chirpstack-gateway-bridge is still publishing all the data to “eu868/gateway/+/event/+”, and topic “$share/chirpstack/eu868/gateway/+/event/+” is not existing, I don’t get any messages:
INFO chirpstack::gateway::backend::mqtt: Subscribing to gateway event topic region_id=eu868 event_topic=$share/chirpstack/eu868/gateway/+/event/+
chirpstack-1
ERROR chirpstack::gateway::backend::mqtt: MQTT error error=Mqtt state: Subscribe failed with reason ‘ImplementationSpecific’
Can someone please help me to solve this issue?

Kind regards

Shared subscriptions should be supported by any MQTT v5 compliant message broker. Search this forum, there are a number of discussions about it.

You may need to update your broker, or at least look into what it supports.