MongooseError: Operation `tests.findOne()` buffering timed out after 10000ms - node.js

Question

I will be very grateful if you could help me with this issue. Although there are many similar problems, I couldn't find a solution about mine.
Everything is okay, when I'm starting the app- it is connected to the port and the database, but then when I'm using a test post request from insomnia with the url http://localhost:3001/api/testRouter/test
and body {
"testText": "Art",
"testNumber": 1
}. I want a new test to be created and sent to the mongodb atlas, but I'm getting this error:
MongooseError: Operation tests.findOne() buffering timed out after 10000ms
at Timeout. (C:\Users\gabri\OneDrive\Desktop\ip-first\ip-first\server\node_modules\mongoose\lib\drivers\node-mongodb-native\collection.js:198:23)
at listOnTimeout (internal/timers.js:551:17)
at processTimers (internal/timers.js:494:7)
This is my db.js file, where I create connection with mongoose:
const mongoose = require('mongoose')
const dotenv = require('dotenv')
dotenv.config()
const connectDB= async()=>
{
try
{
await mongoose.connect(process.env.DATABASE_ACCESS,
{
useNewUrlParser: true,
useUnifiedTopology: true,
useCreateIndex: true
},
()=>
{
console.log("Database connected")
})
}
catch(err)
{
console.log("Error in db connection", err)
}
}
module.exports=connectDB;
This is my test model, which I'm using for testing:
const mongoose = require('mongoose')
const TestSchema = new mongoose.Schema({
testNumber:
{
type:Number,
required: true
},
testText:
{
type: String,
required: true,
trim: true
}
})
const Test = mongoose.model('Test', TestSchema);
module.exports=Test;
This is my test controller, which I'm using it for testing as well:
const Test = require('../models/Test')
exports.testControllerCreate =async(req,res)=>
{
console.log("in router") // it is printed on the console
console.log("body" , req.body) // it is printed on the console
const {testText, testNumber} = req.body;
console.log("check testText", testText) //it is printed on the console
console.log("check testNumber", testNumber) //it is printed on the console
try{
let test= new Test();
test.testText=testText;
test.testNumber=testNumber;
const existingTest = await Test.findOne({testText: testText})
if(existingTest)
{
return res.status(401).json({errorMessage: "Test already exists"})
}
await test.save();
res.status(200).json({successMessage: `Test successfully ${test} created`})
}
catch(err)
{
console.log("err", err)
res.status(500).json({errorMessage: 'Server error'})
}
}
These are my routes:
const express = require('express')
const router=express.Router()
const {testControllerCreate} = require('../controllers/testController')
console.log("router")
router.post('/test', testControllerCreate)
module.exports=router;
And this is my index.js file
const express=require('express')
const app=express()
const cookieParser=require('cookie-parser')
const cors=require('cors')
const connectDB=require('./database/db')
const testRouter = require('./routes/testRoute')
const { connect } = require('./routes/testRoute')
//middlewares
app.use(cors())
app.use(express.json())
app.use(cookieParser())
app.use("/api/testRouter", testRouter)
connectDB();
app.listen(3001, ()=>
{
console.log("running on port 3001 new try")
})
I really hope that someone could help me. I've tried changing the ips in the network access section in the mongodb atlas, checked my url if the password and the username are the same as these from the mongodb atlas, I tried using some extra async await methods, but nothing helped.