POST request working on localhost, but cannot POST to AWS - node.js

Question

I can't solve my problem. I stuck in this issue for a long time, so now I'm asking you.
Here, this was my question before I posted.
I made a mistake that I didn't export module at that time.
Now, I tested in localhost, it works well.
However, if I test with postman, it doesn't work at all like bellow
If you guys have this experience and resolved, then please give me some tips to resolve this issue.
It's my app.js, routes/imgFiles.js and models/imgFiles.js
app.js
const express = require('express');
const bodyParser = require('body-parser');
const app = express();
const port = process.env.PORT || 3000;
const path = require('path');
const favicon = require('serve-favicon');
const logger = require('morgan');
const cookieParser = require('cookie-parser');
app.use(bodyParser.json({ limit: '10mb' }));
app.use(bodyParser.urlencoded({ extended: false }));
app.use(express.static(path.join(__dirname, '../awesome-drill/dist')));
app.use(logger('dev'));
const appRoutes = require('./routes/app');
const imgRoutes = require('./routes/imgFiles');
const userRoutes = require('./routes/user');
app.use(imgRoutes);
app.use(userRoutes);
app.use(appRoutes);
app.use(cookieParser());
app.use((req, res) => {
res.setHeader('Access-Control-Allow-Origin', '*');
res.setHeader('Access-Control-Allow-Headers', 'Origin, X-Requested-Width, Content-Type, Accept');
res.setHeader('Access-Control-Allow-Methods', 'POST, GET, PATCH, DELETE, OPTIONS');
});
app.use(express.static('routes'));
app.get('*', (req, res) => {
res.sendFile(path.join(__dirname, '../awesome-drill/dist/index.html'));
});
app.listen(port, () => {
console.log(`Server is up on port ${port}`);
});
models/imgFiles.js
var express = require('express');
var router = express.Router();
var ImageFile = require('../models/imageFiles');
var multer = require('multer');
var storage = multer.diskStorage({
destination: function (req, file, cb) {
cb(null, '../img/') // Set directory
},
filename: function (req, file, cb) {
cb(null, file.name) // Set file name
}
});
var img = multer({ storage: storage });
router.post('/uploadFiles',img.single('imgfile'), (req, res) => {
var imageFile = new ImageFile({
imgName: req.body.imgName,
imgType: req.body.imgType,
imgSize: req.body.imgSize,
imgContent: req.body.imgContent
});
imageFile.save((err, result) => {
if (err) {
return res.status(500).json({
title: 'An error occured',
error: err
});
}
res.status(201).json({
message: 'Img saved',
obj: result
});
});
});
module.exports = router;
models/imgFiles.js
var {mongoose} = require('../db/mongoose');
var uniqueValidator = require('mongoose-unique-validator');
var schema = mongoose.Schema({
imgName: {
type: String,
},
imgType: {
type: String,
},
imgSize: {
type: Number,
},
imgContent: {
type: String,
},
});
schema.plugin(uniqueValidator);
module.exports = mongoose.model('ImageFile', schema);