exu

I’m also not a programmer, you’ll find my longest comments to explain why I’ve done some terrible mangling, what this does and how.

I think it’s just using MQTT, so block network access and use HomeAssistant

I’d stick to using the host IP for communication between pods. It keeps the separation of different pods intact, makes it easier to add new services and if you ever get a second machine for containers you can continue doing it the same way just with a different IP.

The AIO container is so terrible, like, that’s not how you’re supposed to use Docker.
It’s unclear whether OP was using that or saner community containers, might just be the AIO one.