Apt-get related issue

[Armin@netPI]

Well you are running into the same issue as the user Tad in this post https://forum.hilscher.com/thread-269.html.

I see in your log file that mosquitto be default is using a default mosquitto.conf file. But in this default mosquitto.conf file "anonymus logins" as Node-Red is performing it is disabled by default as explained in the very official mosquitto container documentation here https://mosquitto.org/documentation/migrating-to-2-0/

So either
a.) you create your own corrected mosquitto.conf file and map it into the container during container start
b.) you post edit the default mosquitto.conf file now in your started container manually using netPI container console mode and edit the file in the container's folder /mosquitto/mosquitto.conf with a text ediutor like "vi"

In both cases a.) and b.) the *.conf file has to contain the two lines 

Code:

listener 1883
allow_anonymous true

After editing the *.conf file restart the container and your mosquitto container is running find and accept anonymous logins of Node-RED.