Thank you @chopmann & @jjanderson for your responses.
I am building the setup in AWS with an ECS cluster which is similar to docker-compose. So yes, it is a setup with N-Machines and they are grouped in the graphic like that, because they “live” on the same machine.
You mentioned that MQTT has some stateful properties. Do you know more about this?
Also thank you for the idea with the bridge. I am not sure it is possible with my setup, but I will definitely have a look at it, because it would make my setup much easier.