MQTT recurring error message

Configuration
1

Some months ago I installed Z2MQTT and the MQTT app, with no special configuration (defaults all the way). And it works fine with a whole load of zigbee devices.

I’m now looking into how to get a couple of Fully Kiosk tablets onto MQTT so I can use their cameras as motion detectors, and it turns out I haven’t the faintest idea how to do that - but that’s a different topic. While poking around, I looked at the MQTT logs and found the following error message coming up every 5 seconds.

2026-08-29 17:30:56: New connection from fd0c:ac1e:2100::1:43288 on port 1883. error: received null username or password for unpwd check 2026-08-29 17:30:56: Client c6ed1456 [fd0c:ac1e:2100::1:43288] disconnected: not authorised.
How do I find out what device is being referred to?

2

That looks like it’s an IPv6 address.
Some Googln reveals that it is the internal IPv6 address assigned to the Docker bridge network (hassio) inside Home Assistant OS (HAOS

3

Thanks… but the mystery deepens. I’m running on Home Assistant Yellow, which I believe doesn’t use Docker?

4

HA always run inside a Docker Container