Errno 111 Connection refused error when trying to connect to mongodb container

Question

I am trying to set up a flask app using nginx reverse proxy and my flask should be talking to mongodb backend but I can seem to be able to get mongodb to setup the default admin user so. I can connect to the database but when I try to authenticate using the admin user credentials I get "authentication failure error"!

Here is my docker-compose.yaml file:

version: '3.7'
services:

  mongodb:
      env_file:
          - .env
      image: mongo:5.0.6
      ports:
        - "30000:27017"
      container_name: groupkash-mongodb
      restart: always
  #    command: echo 'Hello'
      environment:
        - MONGODB_DATA_DIR=/data/db
        - MONDODB_LOG_DIR=/dev/null
        - MONGO_INITDB_ROOT_USERNAME=${MONGO_INITDB_ROOT_USERNAME}
        - MONGO_INITDB_ROOT_PASSWORD=${MONGO_INITDB_ROOT_PASSWORD}
      volumes:
        - ./mongodbdata:/data/db
      networks:
        - backend
  flask:
    env_file:
      - .env
    build:
      context: .
      dockerfile: Dockerfile
    container_name: groupkash-flask
    image: groupkash-gunicorn-flask:v1.0
    restart: always
    environment:
      - APP_ENV=${APP_ENV}
      - APP_DEBUG=${APP_DEBUG}
      - APP_PORT=${APP_PORT}
      - MONGO_INITDB_ROOT_USERNAME=${MONGO_INITDB_ROOT_USERNAME}
      - MONGO_INITDB_ROOT_PASSWORD=${MONGO_INITDB_ROOT_PASSWORD}
#      - MONGO_URI=mongodb://${MONGO_INITDB_ROOT_USERNAME}:${MONGO_INITDB_ROOT_PASSWORD}@localhost:30000/
    volumes:
      - ./appdata:/app/data
    depends_on:
      - mongodb
    networks:
      - frontend
      - backend

  webserver:
    build:
      context: nginx
      dockerfile: Dockerfile
    image: groupkash-webserver:v1.0
    container_name: groupkash-webserver
    restart: always
    environment:
      APP_ENV: "prod"
      APP_NAME: "webserver"
      APP_DEBUG: "true"
      SERVICE_NAME: "webserver"
    ports:
      - "80:80"
      - "443:443"
    volumes:
      - ./nginx/nginxdata:/var/log/nginx
    depends_on:
      - flask
    networks:
      - frontend

networks:
  frontend:
    driver: bridge
  backend:
    driver: bridge

volumes:
  mongodbdata:
    driver: local
  appdata:
    driver: local
  nginxdata:
    driver: local

I am passing the environment values via a "gunicorn_config.py" file. This is my connection string used:

MONGO_URI=mongodb://user:[email protected]:30000/database 

Error message:

Error: 172.21.0.2:30000: [Errno 111] Connection refused, Timeout: 30s, Topology Description: <TopologyDescription id: 627bbf91d21f9dbb2f1e4267, topology_type: Unknown, servers: [<ServerDescription ('172.21.0.2', 30000) server_type: Unknown, rtt: None, error=AutoReconnect('172.21.0.2:30000: [Errno 111] Connection refused')>]>]

And the docker network inspect command shows mongodb and flask are on the same network:

"Containers": {
            "8e5d145e88ea35a0bf974f8556ad37739853b73803d8f002c82051a5332cdc6a": {
                "Name": "groupkash-flask",
                "EndpointID": "401c504ab71f5b5f8c97696bbb6635ff453dce158a382c5bf3706240b8222ffa",
                "MacAddress": "02:42:ac:15:00:03",
                "IPv4Address": "172.21.0.3/16",
                "IPv6Address": ""
            },
            "a9612c8ec181d5b574e7bc9067fa93d71b77b0d1de6a1a86c6706a028d52017d": {
                "Name": "groupkash-mongodb",
                "EndpointID": "3680f8eaf19cf42223f97ac90a3993b95848f14d69316c501e15d9549dc16de1",
                "MacAddress": "02:42:ac:15:00:02",
                "IPv4Address": "172.21.0.2/16",
                "IPv6Address": ""
            }
        },