I can create things, set up connections and apply the connection policy to the thing so I can submit telemetry from a thing via HTTP and MQTT and receive it on my MQTT server/connection. I've got all this working.
But when I try to switch to using gateway mode via HTTP or MQTT adaptor it no longer works.
I'm not sure how to authorise a thing to act on behalf of another thing.
When I use the HTTP adaptor I get "gateway unknown, disabled or not authorized to act on behalf of device".
As Kai Hudalla pointed out the when registering a device you can set the via property to authorise a gateway to act on it's behalf and its documented at https://docs.bosch-iot-suite.com/hub/general-concepts/gatewaymode.html