Cannot connect node js app to mongodb running in a docker swarm

I am trying to deploy nodejs app in docker swarm. However I'm struggling to make it connect to the mongodb service. Below is my docker-compose file

version: '3'
services:
  moitrack-teltonika-parser:
    build: .
    image: moitrack/moitrack-teltonika-parser:1.0.14
    ports:
      - "5001:5001"
    networks:
      - web
    deploy:
      mode: replicated
      replicas: 2
      update_config:
        parallelism: 2
        delay: 10s
      restart_policy:
        condition: on-failure
        delay: 5s
        max_attempts: 3
        window: 120s
    depends_on: 
      - db
  db:
    image: mongo
    command: mongod --bind_ip_all
    ports:
    - "27017"
    volumes:
    - mongodata:/data/db
    restart: "always"
    deploy:
      placement:
        constraints: [node.role == manager]
    networks:
    - web
volumes:
  mongodata: {}
      
networks:
  web:
    external: true

This is the node js script

var express = require("express");
const mongoose = require('mongoose');
var server = express();

const options = {
    useNewUrlParser: true,
    reconnectTries: Number.MAX_VALUE,
    reconnectInterval: 500,
    connectTimeoutMS: 10000,
  };

const DB_URI = 'mongodb://db:27017/moiponeGateKeeper';

mongoose.connect(DB_URI, options).then(() => {
    console.log("database connected");

}).catch(err => console.log(err));

server.listen(5001, () => { console.log("Server started"); });

I get the error below when I view the node service in the docker swarm. enter image description here

Copyright Notice：Content Author:「Mosa Sello」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/67380974/cannot-connect-node-js-app-to-mongodb-running-in-a-docker-swarm