Absolute beginner to Home Assistant
Browsed the forum – found many complicated questions and complicated responses, none close match.
Appreciate if someone can steer me on any one of these things.
Long sorry – try to fill in the situation and (lack of understanding)
Raspberry pi 4 – seems to run home assistant ok.
- Installation methodHome Assistant OS
- Core2026.5.4
- Supervisor2026.05.0
- Operating System17.3
- Frontend20260429.4
Arduino with DHT22 – “loop()” reports to Serial temp & humidity attempts to (instance of PubSubClient).connect - fails. (return 0, .state 5)
Seen in help that I shouldn’t need to speak YAML as Home Assistant does all.
Added MQTT and mosquito to home assistant.
Issue nothing happens. (No suggestion that home assistant sees sensor, device, MQTT message, well, sees nothing really)
Turn on MQTT diagnostics – does not seem to exist anywhere in any menu I found.
Setting .. mosquito .. “Reconfigure”
Promising: but – shows “Username” : homeassistant” and “Password”: “__**password_not_changed**__”
Online help says create a new user
Online help says don’t create a new user
Online help says don’t use “homeassistant”
Online help says should not need to use a username or password.
Arduino PubSub Client
My example code I found for Arduino
Uses, as above
int retCode = mqttClient.connect(CLIENT_ID); -
which reading I interpret to be anonymous MQTT. I also read that this is not disabled by default.
retCode = 0 client.State reports 5
My attempt to change to match that below,
int retCode = mqttClient.connect(CLIENT_ID,"homeassistant","__**password_not_changed**__");
int retCode = mqttClient.connect(CLIENT_ID); -
retCode = 0 client.State reports 5
Not going anywhere.
If I try to change things in Setting .. mosquito .. “Reconfigure”
To try some of the conflicting directives
Changing username and password, instead of updating something for me says
MQTT
Please enter the connection information of your MQTT broker.
Failed to connect
Err, that was what I was trying to change. (Clearly not what that is for)
If I hit “Submit” unchanged it says reconfigure – but seems the only reconfiguration is takes is no change.
Clearly I am missing something fundamental. 
Home Assistant “add device” leads to “select brand” – so a little out in the cold there.
Home Assistant setting MQTT … Add MQTT device
Leads to [Configure MQTT device details] – promising
Added a device [Hal2] with 4 “entities”
Humidity, temperature, passive IR sensor and IP address message.
Still nothing arrives.
Extra missed info
Ethernet PI and arduino on same hub.
Arduino (Serial console debugging) reports it gets a DHCP address (1 different from the pi) so believe it is networking appropriately.
My pc (arp -a) sees pi on the net,but no report for the arduino.
Totally understand that for some knowledgeable people the obvious answer is …Just the rather obvious … jump into 20 things I know nothing about and configure them ….
But, any simple pointers to what I’m missing, or which info to believe or ignore would be nonetheless appreciated.
Or a pointer to the forum questions I missed?
Cheers
OK, long story short - I created a new "people" user and it all works.
Anyone who can point me to how it is supposed to work without this, as mentioned in the documentation wins a virtual chocolate fish.
Thanks to anyone who viewed and considered helping.