MongoServerSelectionError: connect ECONNREFUSED 127.0.0.1:27017 at Timeout._onTimeout - node.js

Question

Why am i getting this error?
I am trying to send the audio file I have on the front end using form data to the backend, where I'm using multer and gridfs to send the file to mongoDB. I have been a lot issues trying to do this with an audio file.
Why am i getting this error? I am trying to send the audio file. I have on the front end using form data to the backend where I'm using multer and gridfs to send the file to mongoDB. I have been a lot issues trying to do this with an audio file.
App.js
import React, { useState } from 'react';
function AudioUpload() {
const [file, setFile] = useState(null);
const handleFileChange = (e) => {
setFile(e.target.files[0]);
};
const handleSubmit = async (e) => {
e.preventDefault();
const formData = new FormData();
formData.append('audio', file);
try {
const response = await fetch('http://localhost:4003/upload', {
method: 'POST',
body: formData,
});
const data = await response.json();
console.log(data);
} catch (error) {
console.error(error);
}
};
return (
<div>
<form onSubmit={handleSubmit}>
<div>
<input type="file" id="audio" name="audio" accept="audio/*" onChange={handleFileChange} />
</div>
<button type="submit" disabled={!file}>Upload</button>
</form>
</div>
);
}
export default AudioUpload;
Server.js
const express = require('express');
const mongoose = require('mongoose');
const multer = require('multer');
const Grid = require('gridfs-stream');
const { GridFsStorage } = require('multer-gridfs-storage');
const cors = require("cors");
const app = express();
app.use(cors());
const conn = mongoose.createConnection('mongodb+srv://jordandeeds31:Jd400089#cluster0.iwva5ci.mongodb.net/grid2?retryWrites=true&w=majority', {
useNewUrlParser: true,
useUnifiedTopology: true,
});
let gfs;
conn.once('open', () => {
gfs = Grid(conn.db, mongoose.mongo);
gfs.collection('audioFiles');
console.log("connected to db");
});
const storage = new GridFsStorage({
url: 'mongodb://localhost/mydatabase',
file: (req, file) => {
return {
filename: file.originalname,
bucketName: 'audioFiles',
};
},
});
const upload = multer({ storage: storage });
const audioSchema = new mongoose.Schema({
filename: { type: String, required: true },
contentType: { type: String, required: true },
fileId: { type: mongoose.Schema.Types.ObjectId, required: true },
});
const Audio = conn.model('Audio', audioSchema);
app.post('/upload', upload.single('audio'), async (req, res) => {
try {
const { originalname, mimetype } = req.file;
const fileId = req.file.id;
const audio = new Audio({
filename: originalname,
contentType: mimetype,
fileId,
});
await audio.save();
res.status(200).json({ message: 'File uploaded successfully' });
} catch (err) {
console.error(err);
res.status(500).json({ message: 'Error uploading file' });
}
});
app.listen(4003, () => {
console.log('Server listening on port 4003');
});