I am learning , MERN stack , the problem is I created a delete function to delete a json item on my db (mongoDB), but whe i make test on it on postman I got an error (Error: connect ECONNREFUSED 127.0.0.1:4000)

the express.js function

const deleteJob = async (req, res) => {

    const { id } = req.params

    if (!mongoose.Types.ObjectId.isValid(id)) {
        return res.status(400).json({ error: 'No such workout' })
    }

    const job = await Job.findOneAndDelete({ _id: id })

    if (!job) {
        return res.status(400).json({ error: 'No such workout' })
    }

    res.status(200).json(job);
}```


the express Router 

const express = require(‘express’)

const router = express.Router()

//get Functions from controller
const { createNewJob, getJobs, getSingleJob, deleteJob, updateJob } = require(‘../controller/controller’)

//Router Routes

//get all jobs
router.get(‘/’, getJobs)

//get a job
router.get(‘/:id’, getSingleJob)

//add new Job
router.post(‘/’, createNewJob)

router.delete(‘/:id’, deleteJob)

I expect to solve this probleem .