MQTT connection fails > how to debug?

My docker container with homeassistant is always kept up to date thanks to watchtower.
Current version is:
Home Assistant 2023.9.3 Frontend 20230911.0 - latest

I cannnot connect to my mosquitto mqtt container, I only get this message:

It works with the mqtt explorer, so I can receive all messages from there.

There is nothing in the current logs:


2023-09-26T06:47:39.096872953Z 2023-09-26 08:47:39.094 WARNING (MainThread) [homeassistant.components.websocket_api.http.connection] [140210508404672] from 192.168.178.67 (Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:109.0) Gecko/20100101 Firefox/117.0): Disconnected: Did not receive auth message within 10 seconds

There is only something in the old logs:

2023-09-25T15:32:44.824561388Z 2023-09-25 17:32:44.821 ERROR (MainThread) [homeassistant.components.mqtt.client] Failed to connect to MQTT server due to exception: timed out
2023-09-25T15:33:04.382135035Z 2023-09-25 17:33:04.380 ERROR (SyncWorker_1) [homeassistant.util.package] Unable to install package croniter==1.3.8: ERROR: Could not install packages due to an OSError: [Errno 22] Invalid argument: '/usr/local/lib/python3.11/site-packages/croniter-1.0.6.dist-info/'
2023-09-25T15:33:04.382325052Z
2023-09-25T15:33:04.382355245Z WARNING: Ignoring invalid distribution ~roniter (/usr/local/lib/python3.11/site-packages)
2023-09-25T15:33:04.382388189Z WARNING: Skipping /usr/local/lib/python3.11/site-packages/croniter-1.0.6.dist-info due to invalid metadata entry 'name'
2023-09-25T15:33:04.382409036Z WARNING: Ignoring invalid distribution ~roniter (/usr/local/lib/python3.11/site-packages)
2023-09-25T15:33:04.382429713Z WARNING: Skipping /usr/local/lib/python3.11/site-packages/croniter-1.0.6.dist-info due to invalid metadata entry 'name'
2023-09-25T15:33:04.382461642Z WARNING: Ignoring invalid distribution ~roniter (/usr/local/lib/python3.11/site-packages)
2023-09-25T15:33:04.382482524Z WARNING: Skipping /usr/local/lib/python3.11/site-packages/croniter-1.0.6.dist-info due to invalid metadata entry 'name'
2023-09-25T15:33:04.382503615Z
2023-09-25T15:33:04.382523649Z [notice] A new release of pip is available: 23.1.2 -> 23.2.1
2023-09-25T15:33:04.382555705Z [notice] To update, run: pip install --upgrade pip