MQTT on Arduino not working

Question

I\'m using Arduino Uno and Wi-Fi shield. I\'m trying to implement MQTT protocol for communication and I tried two libraries for Arduino. First one is Knolleary\'s PubSubClient:

Answer 1

As mentioned in the comments

When using example code on public brokers make sure you change the client id to something random as the odds of clashing with somebody else are pretty high. Because client ids have to be unique else they will cause a reconnection storm