Unable to access a specific route in my express server

Question

I am new to Web Development & have started building a MERN app as a side project. I am encountering the below problem.

When I am trying to access a route in my routes file, I was unable to access it. It is showing this error in Postman when trying to access it :

GET http://localhost:4000/api/matches/matchlist
Error: connect ECONNREFUSED ::1:3000
Request Headers
User-Agent: PostmanRuntime/7.31.1
Accept: */*
Postman-Token: fa77215b-eb3c-4667-8b8d-63ffc2bd84be
Host: localhost:4000
Accept-Encoding: gzip, deflate, br
Connection: keep-alive 

My server file :

const express = require('express');
const connectMongDB = require('./config/connectMongoDB');

// Connecting the matches.js file to the server.js file
const matches = require('./routes/matches');

// MongoDB connection
connectMongDB();

const app = express();

app.use(express.json());

const port = process.env.PORT || 4000;

// Using matches middleware for matches management routes
app.use('/api/matches', matches);

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

My matches routes file :

const express = require('express');
const router = express.Router();
const Match = require('../database_models/matchModel');

// Get all matches
router.get('/', async (req, res) => {

  //console.log("User is authenticated");
  try {
    const matches = await Match.find();
    console.log(matches);
    res.json(matches);
  } 
  catch (err) {
    console.error(err.message);
    res.status(500).send('Server Error');
  }
  
});

// Get match by id
router.get('/:id', ensureUserAuthenticated, async (req, res) => {
  
  try {
    const match = await Match.findById(req.params.id);
    if (!match) {
      return res.status(404).json({ msg: 'Match not found' });
    }
    res.json(match);
  } 
  catch (err) {
    console.error(err.message);
    res.status(500).send('Server Error');
  }
  
});

router.get('/matchlist', (req,res) => {
  res.send("Success");
});


module.exports = router;

I was able to access the route '/api/matches/' but getting the above said error when trying to access '/api/matches/matchlist/' route.

And it also showing Internal Server Error(500) in the console box.

Can someone please tell me what's going wrong.