ConnectionRefusedError: [Errno 111] Connection refused - MQTT - sockets

Question

I am very new to socket and communication using MQTT. Already spent hours but dont know what is wrong. Kindly help me to fix this error.
I am using the below code,
import socket
import json
from random import randint
from inference import Network
import paho.mqtt.client as mqtt
HOSTNAME = socket.gethostname()
IPADDRESS = socket.gethostbyname(HOSTNAME)
MQTT_HOST = IPADDRESS
MQTT_PORT = 1883 ### TODO: Set the Port for MQTT
MQTT_KEEPALIVE_INTERVAL = 60
client = mqtt.Client()
client.connect(MQTT_HOST,MQTT_PORT,MQTT_KEEPALIVE_INTERVAL)
And the error and traceback is shown below,
(venv) root#119d16139409:/home/workspace# python app.py | ffmpeg -v warning -f rawvideo -pixel_format bgr24 -video_size 1280x720 -framerate 24 -i - http://0.0.0.0:3004/fac.ffm
Traceback (most recent call last):
File "app.py", line 145, in <module>
main()
File "app.py", line 141, in main
infer_on_video(args, model)
File "app.py", line 74, in infer_on_video
client.connect(MQTT_HOST,MQTT_PORT,MQTT_KEEPALIVE_INTERVAL)
File "/opt/intel/openvino_2019.3.376/deployment_tools/model_optimizer/venv/lib/python3.5/site-packages/paho/mqtt/client.py", line 937, in connect
return self.reconnect()
File "/opt/intel/openvino_2019.3.376/deployment_tools/model_optimizer/venv/lib/python3.5/site-packages/paho/mqtt/client.py", line 1071, in reconnect
sock = self._create_socket_connection()
File "/opt/intel/openvino_2019.3.376/deployment_tools/model_optimizer/venv/lib/python3.5/site-packages/paho/mqtt/client.py", line 3522, in _create_socket_connection
return socket.create_connection(addr, source_address=source, timeout=self._keepalive)
File "/usr/lib/python3.5/socket.py", line 711, in create_connection
raise err
File "/usr/lib/python3.5/socket.py", line 702, in create_connection
sock.connect(sa)
ConnectionRefusedError: [Errno 111] Connection refused