MQTT not working, 2020

Hi, I’m having trouble implementing MQTT on a newish install of

After installing the add-on ‘Mosquitto’, I cannot get it to start.

I have an IOS app called MQTTool which works great, this successfully connects to ‘a’ broker on the same IP as which I understand is the default built-in broker in home assistant. I can pub/sub to a couple of Arduino coded MQTT sketches but my Tasmotas are not connecting to the broker when watching the console in the Tasmota ui.

I originally set up with the configuration.yaml mqtt: pointing to the IP of a different Raspberry Pi, that was running Mosquitto and Node-RED. Everything, until yesterday was working fine then the Mosquitto had the old problem ‘port 1883 already in use’ I uninstalled it from the Rasbian after failing to sort it. So I decided to run with the Mosquitto add-on.

No log appears in the add-on and the very simple configuration that i have seen on youtube several times will not start on my

I only need and want to use one MQTT broker, can anyone give me any tips to aid troubleshooting this?