Then I setup the RAK server gateway back-end MQTT to point to my Pi mosquitto, expecting to start seeing the Gateway MQTT messages (Events/commands etc)… but I dont see any MQTT topics or messages :(.
That would set where the server expects to communicate with gateways.
But it would probably not set how the gateway (specifically the gateway bridge) expects to communicate with the server.
My guess is when you do this, the server stops getting any gateway traffic at all.
You’d need to also change the configuration of the gateway bridge to point to the external MQTT.
But once you do that, there’s essentially no reason to use the internal sever - you’d be bouncing the raw traffic up to the cloud, back down, processing it, then bouncing any downlinks back up and down again. Why would you want to do that?
If you really want to just monitor what is going on in an internal setup, then you probably want to stick with the internal broker, but add a custom component that gets the status messages and forwards them to an external broker, so that this monitoring is outside of the critical operational path.