Express.js/Node.js Responses Before Query Finishes - node.js

Question

I have a local server that is fully functioning when POSTs and GETs are sent from Postman or chrome rest apps etc. However, whenever I send it from an ESP8266 it fails as it follows:
This is my server side code:
router.get('/', function (req, res) {
var person = req.query.id;
console.log("1");
Person.find({person: personID} ,function (err, station) {
if(err) console.log(err.message);
console.log("3");
res.send('test');
console.log("4");
});
console.log("2");
});
Lines below are from console when request is sent from Chrome.
1
2
3
4
GET /api?id=ABKWTltz6Ug 200 21.829 ms - -
And the lines below are from console when request is sent from ESP8266.
1
2
GET /api?id=ABKWTltz6Ug - - ms - -
3
4
As you may notice logs 3 and 4 are after GET response line. My ESP8266 TCP connection lines match the HTTP Message Format:
GET /api HTTP/1.1
Host: *SERVER_IP_ADDRESS*
The problem raised when we switched from PHP to NodeJS backend server. ESP8266 used to connect and operate without problems back then. And FYI, everything also works fine if I remove the Person.find code block and move the res.send('test'); outside.
Another freshly written backend code to hopefully spot the error is below. This is the whole code. Which also returns the same error I've mentioned earlier above:
var express = require('express');
var app = express();
var router = express.Router();
var mongoose = require('mongoose');
var morgan = require('morgan');
app.use(morgan('dev'));
mongoose.connect('mongodb://localhost/test');
//mongoose.Promise = Promise;
var Test = mongoose.model('Test', { name: String });
router.get('/test', function (req, res) {
console.log("1");
var test1 = new Test({
name: "Name"
});
var query = test1.save();
query.then(function (doc) {
res.send('1').end();
console.log('3');
});
console.log("2");
});
app.use('/api', router);
var port = 9000;
app.listen(port,function(){
console.log('server started on', port);
});