How to set up a web server to respond to post requests?

Question

Node.js

I'm trying to make a request to a web server. When the code is hosted on localhost, the requests are processed and the server sends a response. When I upload the code to a remote machine with debian 9 OS, requests are not processed, although there is a ping to the server. I'm testing through the Postman program, postman reports that it could not receive a response.

const http = require('http'),
      mysql = require('mysql'),
      express = require('express'),
      options = require('./config.js'),
      router = express.Router();

let  con = mysql.createConnection(options);
 

router.post('/update/:id', function(req, res){
    (async()=> {
        let schoolNumber = req.params.id;           //выборка данных из школы
        let obj = {};
        try {                           //сохраняем данные в свойства объекта
            obj.subject_schoolboy = await sqlQuery(    //выборка subject у шк
                "SELECT DISTINCT idsubject FROM subject "+
                "INNER JOIN schoolboy ON subject.idsubject=schoolboy.idschoolboy "+
                "INNER JOIN school ON schoolboy.school=school.idschool WHERE school.shortName="+schoolNumber+" AND schoolboy.actuality=1" );
            obj.subject_teacher = await sqlQuery(      //выборка subject у уч
                "SELECT DISTINCT idsubject FROM subject "+
                "INNER JOIN teacher ON subject.idsubject=teacher.idteacher "+
                "INNER JOIN school ON teacher.school=school.idschool WHERE school.shortName="+schoolNumber+" AND teacher.actuality=1" );
  ...............................................................................................................................................................