MQTT Broker connection failure

I can’t connect to my mqtt broker anymore. Seen various posts on this topic but none seem to be what I am experiencing so adding a new one. My log shows and I’ve re-installed the broker with no success. I’m using mqttexplorer to connect but other tools fail as wel.

My configuration is below and I’m using a standard HA user, specially configured for this purpose that used to work. Any thoughts would be greatly appreciated

The best test is a manual MQTT client like https://mqtt-explorer.com/

A walk-through of Mosquitto MQTT server settings may help (note the use of a seperate user configured in the Mosquitto Add-On Configuration tab to avoid HASS credential issues which can fail):

Could you be using IPv6?
I’ve seen disconnections for no obvious reason before as HASS used to only support IPv4 but that was a slightly different error:

If this helps, :heart: this post!

Thanks @FloatingBoater.

I use mqtt-explorer which fails in the same way the mqtt add-on does :frowning: I also use a separate user and I don’t use IPv6 so I think I covered all your basis. But it still doesn’t work

Best I can suggest is a web search for the Client <unknown> disconnected due to protocol error. text, but I bet that’s the first thing you tried! :man_shrugging:

My working broker shows lots of Client <unknown> disconnected type logs, so that’s not the issue.

Can you try a telnet -4 test to check the network layer?

Protocol error and Opening ipv6 listen socket still makes me wonder if your client has started to support IPv6, but that’s still a rather long shot (a Linux client switched to IPv6 DNS automatically, which caused my second linked issue - I changed nothing other than kernel patches).

Remove port 1883 and 1884 in your setting and see if that will work. I see my settings are blank for that 2 ports.

I sorted it out - long story but the RPI had lan and wifi connections, the wifi IP address stopped working so I needed to move the MQTT settings to use the LAN IP address instead. Changed that and it all works.

So basically: it’s just me being stupid! Thanks for your help