我试图连接到MongoDB中的数据库，但它没有连接，我正在使用此代码（index.js）

const express = require('express');
const mongoose = require('mongoose');

let app = null;
let port = null;
let MONGO_URL = null;


const initVar = async () => {
    port = 9000;
    MONGO_URL = "mongodb+srv://mc3453:xxxxxx@unify.dyadwbb.mongodb.net/customer?retryWrites=true&w=majority";
    app = express();
};

mongoose.set('strictQuery', true);
const connectDB = async () => {
    try {
        await mongoose.connect(MONGO_URL, {
            useNewUrlParser: true,
            useUnifiedTopology: true,
        });
        console.log('MongoDB connected');
    } catch (error) {
        console.log(error);
    }
};

const listentoPort = async () => {
    app.listen(port, async () => {
        console.log(`Server is running on port ${port}`);
    });
};

initVar().then(() => {
    listentoPort().then(() => {
        connectDB();
    });
});

连接字符串为：mongodb+srv://mc3453:<password>@unify.dyadwbb.mongodb.net/?retryWrites=true&w=majority

我得到的错误是：

Error: queryTxt ETIMEOUT unify.dyadwbb.mongodb.net
    at QueryReqWrap.onresolve [as oncomplete] (node:internal/dns/promises:251:17) {
  errno: undefined,
  code: 'ETIMEOUT',
  syscall: 'queryTxt',
  hostname: 'unify.dyadwbb.mongodb.net'
}

我甚至添加了我的IP地址，但每次我切换回该网站，它说你的IP地址不在那里，但我又添加了回来

我怎么能解决这个问题，请帮助我解决这个问题，我是新来的，请帮助我