This isn't exactly a HG issue, but I'm sure others here could run into this if not using the built-in MQTT broker. Mosquitto is one of the more popular brokers but the standard repository only has version 0.15 available. I was having issues connecting an ESP8266 so I upgraded the repository and was able to get a current version of Mosquitto (1.4.10) but now nothing connects to it from another machine. I can use the local pub/sub and it will work but that's it.
I have an Arduino UNO running PubSubClient that was working on 0.15 and now will not connect. I installed MyMQTT for my Android phone and it will connect to test brokers but not the RPi. I tried the ESP8266 with test brokers successfully but failed to connect to the RPi.
I'm sure there's some difference between 0.15 and 1.4.10 that is the issue and most likely just a setting that can be changed. However, I can't figure it out for the life of me! If anyone has 1.4.10 (or anything over 0.15 really) running on an RPi, PLEASE chime in!