title: Mqtt broker is disconnecting frequently even though it has a unique client id
body: <p>Hi I have a mqtt broker up and running. I am connecting to it from python using paho-mqtt. 
  Code</p>
  
  <pre><code>def on_connect(client, userdata, flags, rc):
      if rc==0:
          print("connected OK Returned code=",rc)
      else:
          print("Bad connection Returned code=",rc)
  
      print("Subscribing to topic","data/#")
      client.subscribe("data/#")
  
  
  def on_disconnect(client, userdata, rc):
     print("Client Got Disconnected")
     if rc != 0:
         print('Unexpected MQTT disconnection. Will auto-reconnect')
  
     else:
         print('rc value:' + str(rc))
  
  broker_address="ip"
  port = 'port'
  print("creating new instance")
  client = mqtt.Client(clean_session=True) #create new instance
  client.on_connect = on_connect
  client.on_message = on_message #attach function to callback
  client.on_disconnect = on_disconnect
  
  print("connecting to broker")
  client.connect(broker_address, port=port,) #connect to broker
  client.loop_forever() #stop the loop
  
  </code></pre>
  
  <p>I am using the same code in multiple scripts ,connecting to broker and subscribing to a topic. The frequency of disconnection was less when there were 5-6 scripts. I have around 12-13 scripts connecting to the broker and frequency of disconnects has increased significantly. Is there some thing wrong with the connection in the scripts or its about the broker. Can someone help me with this?</p>