Strange issue, gateways connected via mqtt bridge are offline

We have 10 RAK gateways connected to chirpstack. Few days ago, all but one went offline. All are with identical configuration. They are using the Chirstack MQTT Gateway Bridge.

We switch on the gateway to semtech UDP packet forwarder instead and they went back online.

Anyone ever encounter this behavior?
Here is the mosquitto log, is it indicating any issues?