MQTT Broker

Yes you can use Eclipse Mosquitto but I think it is only via Docker (I had it on my father’s setup), otherwise you can install it via brew (this is my choice), and it works fine since yesterday now, no restart necessary.

Yes I did mine via homebrew too and unless you have reason for docker brew is easiest way for it to just work on you indigo server Mac.

thank you both.
Mosquitto is now installed on my computer.
How do I point Indigo to this broker?

If it's installed on the same system as Indigo (and the MQTT Broker plugin), then just disable the Broker plugin and restart Mosquitto. They're both going to use the same port.

You will need to edit the Mosquitto config file and make sure it's using the default port and to set a user/password.

From terminal,

bSrvr1911:~ RSS$ brew services start mosquitto
Service `mosquitto` already started, use `brew services restart mosquitto` to restart.
bSrvr1911:~ RSS$

and it is listed as a process in the Activity Monitor, but it is not in the "Application" folder. I'm afraid I have no idea how to configure it? Is the default port 1883?

Yes that’s the default port. Download Mqtt explorer app or similar on the Mac and you can view the server and messages easily.