irregular arbitrarily Cross-Origin request blocked error in Django on Ionos hosting - reactjs

Question

I am currently making a quiz project for school. The quiz is supposed to evaluate in the front-end, which works perfectly fine, and after that it should send the information to the backend. The backend should save the details to the database and after that it should send the information back to the front-end. The front-end should show a message with some details about how you performed compared to all the others, the information is gotten from the database.
So, the weird thing about all that is that it works sometimes and sometimes not. If I test it on localhost, the code works perfectly fine. The error only occurs on the Ionos server (I got a hosting contract so I do not have access to the console).
Here is the link to my website: https://tor-netzwerk-seminarfach2024.com/ . If you click on the upper left corner and then on the quiz button, you will get to the quiz. If I look at the console and network analytics, when the error occurs, the following message shows up:
Cross-Origin request blocked: The same source rule prohibits reading
the external resource on https://api. tor-netzwerk-seminarfach2024.
com/apache-test/. (Reason: CORS request failed).
https://api.tor-netzwerk-seminarfach2024.com/apache-test/ is my backend and https://tor-netzwerk-seminarfach2024.com/ is my front-end.
The settings file in Django is not the problem. To make it clear, the error does not occur always. Sometimes you have to go again to the website and try it one a few more times until you get the error.
If I look at the network analytics, then I see that the client request works as usual, but the answer field from the server is completely empty. Let's move on to the weirdest part of all: the Data actually gets saved in the Database, there is just sometimes no response?
It would be way to much for a minimum working product but here is the most important code. If you want to test it you can just visit the link to my Website:https://tor-netzwerk-seminarfach2024.com/
Server side with Django
from rest_framework.response import Response
from .models import Lead
import json
from .serializer import TestingSerializer
def updateDigits():
leadObj = Lead.objects.all()
currentScore = leadObj[0].sumScore; currentRequests = leadObj[0].sumRequests
valueBtnOne = leadObj[0].buttonOne; valueBtnTwo = leadObj[0].buttonTwo;
valueBtnThree = leadObj[0].buttonThree; valueBtnFour = leadObj[0].buttonFour;
valueBtnFive = leadObj[0].buttonFive; valueBtnSix = leadObj[0].buttonSix;
valueBtnSeven = leadObj[0].buttonSeven; valueBtnEight = leadObj[0].buttonEight;
valueBtnNine = leadObj[0].buttonNine;
return [valueBtnOne,valueBtnTwo,valueBtnThree,valueBtnFour,valueBtnFive,valueBtnSix,valueBtnSeven,valueBtnEight,valueBtnNine,currentScore,currentRequests]
#api_view(["POST"])
def home(request):
body_unicode = request.body.decode('utf-8')
body = json.loads(body_unicode)
result = body["Result"]
isItRight = body["whichOnesRight"]
ip_adress = get_client_ip(request)
queryset = Lead.objects.all()
if Lead.objects.all().exists():
currentValues = updateDigits()
queryset.update(
sumScore = result + currentValues[9],
sumRequests = 1 + currentValues[10],
buttonOne = currentValues[0] + isItRight[0],
buttonTwo = currentValues[1] + isItRight[1],
buttonThree = currentValues[2] + isItRight[2],
buttonFour = currentValues[3] + isItRight[3],
buttonFive = currentValues[4] + isItRight[4],
buttonSix = currentValues[5] + isItRight[5],
buttonSeven = currentValues[6] + isItRight[6],
buttonEight = currentValues[7] + isItRight[7],
buttonNine = currentValues[8] + isItRight[8],
)
currentValues = updateDigits()
else:
obj = Lead()
obj.save()
serializer = TestingSerializer(queryset[0], many =False)
return Response({**serializer.data, "myResult": result})
The Django model
from django.db import models
class Lead(models.Model):
sumScore = models.IntegerField(default=0)
sumRequests = models.IntegerField(default=0)
buttonOne = models.IntegerField(default=0)
buttonTwo = models.IntegerField(default=0)
buttonThree = models.IntegerField(default=0)
buttonFour = models.IntegerField(default=0)
buttonFive = models.IntegerField(default=0)
buttonSix = models.IntegerField(default=0)
buttonSeven = models.IntegerField(default=0)
buttonEight = models.IntegerField(default=0)
buttonNine = models.IntegerField(default=0)
serializer just serializes _ _ all _ _ ...
Front end with React
function evaluateAndCheckQuiz(){
let countNotChosen = howManyNotChosen()
if(countNotChosen){ answerQuestions(countNotChosen); return }
let points = evaluateQuiz()
document.getElementById("scoreText").style.display = "block"
document.getElementById("scoreNumber").textContent = points
return points
}
Calling sendAndGetQuizAverage with evaluateAndCheckQuiz as a parameter
function sendAndGetQuizAverage(points){
const myPostRequest = {
method: 'POST',
headers: {'Content-Type': 'application/json'},
body: JSON.stringify({"Result":points, "whichOnesRight": whichOnesRight}),
};
let data
fetch('https://api.tor-netzwerk-seminarfach2024.com/apache-test/', myPostRequest).then(
(response) => data = response.json()).then(
(data) => {showResultAnalyse(data)})
}
function showResultAnalyse(data){
console.log(data)
let averageScore = (data["sumScore"] / data["sumRequests"]).toFixed(2)
let myResult = data["myResult"]
changeLinksToStatistics([
data["buttonOne"],data["buttonTwo"],data["buttonThree"],
data["buttonFour"],data["buttonFive"],data["buttonSix"],
data["buttonSeven"],data["buttonEight"],data["buttonNine"]
],
data["sumRequests"]
)
swal(
{
text:`${checkWhichText(myResult,averageScore,data["sumRequests"] )}`,
icon: myResult > averageScore ?"success": "error",
button:"Oki doki",
}
);
}