Thanks! You should get a broker set up first and play around on localhost: this makes it easier to get acquainted with what you can and can't do. Experiment wit

Thanks! You should get a broker set up first and play around on localhost: this makes it easier to get acquainted with what you can and can't do. Experiment with the QOS and 'retain' settings to make sure you don't lose messages. I did a writeup at https://petergarner.net/notes.php?thisnote=20190811-Lightweight+Monitoring+System+Using+MQTT.html https://petergarner.net/notes.php?thisnote=20190811-Lightwei... which should give you some ideas. As regards clients I'd recommend the cross-platform MQTT Explorer https://mqtt-explorer.com/ https://mqtt-explorer.com/ and for iOS, I've settled on EasyMQTT which also provides some graphing options. I don't use Android but most of the clients are good (and free). Hope this helps!