MongoNetworkError: failed to connect to server

Question

I am new to Node and Mongo. Trying to develop a web app and its database using mongoDB Atlas. And stuck with above error. I am using following files in this effort.

index.js

const express = require("express");
const mongoose = require("mongoose");
const keys = require("./config/keys");

require("./models/user");
require("./services/passport");

mongoose.connect(keys.mongoURI);
const app = express();
require("./routes/authRoutes")(app);

const PORT = process.env.PORT || 5000;
app.listen(PORT);

---

user.js

const mongoose = require("mongoose");
const { Schema } = mongoose;

const userSchema = new Schema({
    googleID: String,
});

mongoose.model("users", userSchema);

---

passport.js

const passport = require("passport");
const GoogleStrategy = require("passport-google-oauth20").Strategy;
const keys = require("../config/keys");
const mongoose = require("mongoose");

const User = mongoose.model("users");

passport.use(
    new GoogleStrategy(
        {
            clientID: keys.googleClientID,
            clientSecret: keys.googleClientSecret,
            callbackURL: "/auth/google/callback",
        },
        (accessToken, refreshToken, profile, done) => {
            new User({
                googleID: profile.ID,
            }).save(); 
        }
    )
);

---

authRouter.js

const passport = require("passport"); 

module.exports = (app) => {
    app.get(
        "/auth/google",
        passport.authenticate("google", {
            scope: ["profile", "email"], 
    );

    app.get("/auth/google/callback", passport.authenticate("google"));
};

---

keys.js

module.exports = {
googleClientID:

"xxxxxxxxxxxx-3lxxxxll0tflxxxxxxxxov05ovohrvv8.apps.googleusercontent.com", googleClientSecret: "-", mongoURI: "mongodb+srv://userMe:*****************@emaily.fepbh.mongodb.net/testdb?retryWrites=true&w=majority", };

---

I am getting this error in terminal. => (node:25066) UnhandledPromiseRejectionWarning: MongoNetworkError: failed to connect to server [emaily-shard-00-00.fepbh.mongodb.net:27017] on first connect [MongoNetworkError: connection 5 to emaily-shard-00-00.fepbh.mongodb.net:27017 closed]

No database or collection is created as results. Pls help me in here. Thank you very much.