I cant believe im still confused with this but here is the thing. I have an rpi2 with hassio. I use the lovelace interface ui. I use it with some toggle switches to send mqtt messages to an rpi3.
I can never remember who is the broker.
On my configuration.yaml on rpi2/hassio i have a definition line for mqtt where broker is .113 (my rpi3).
But i think i have installed a mosquitto broker via the terminal either on rpi2 or rpi3.
I would think my broker is my rpi2/hassio which is .117.