With aRest.io you are able control your Arduino/Esp from all over the world - but how?
In the Client SourceCode (found here) you only find the PubSubClient, which is an MQTT client.
My Arduino can (during the aRest.h) subscribe to topics in my aRest.io dashboard (http://dashboard.arest.io/) and if I add something to the dashboard the aRest's Broker will inform my Arduino. But here is my error. How can the Broker contact my Arduino behind the firewall? Does the Arduino use hole punching? Is my attempt wrong?