코드 입력하고 저장하고 실행하려는데 갑자기 local:5001에서 연결할 수 없다고 뜨게 되거라구요, 제가 뭘 잘못 건든건가 잘 모르겟습니다;;

from flask import Flask, render_template, request, jsonify
app = Flask(__name__)


from pymongo import MongoClient
import certifi


ca = certifi.where()
client = MongoClient("mongodb+srv://sparta:test@cluster0.zyott9j.mongodb.net/?retryWrites=true&w=majority", tlsCAFile = ca)


db = client.dbsparta 


@app.route('/')
def home():
    return render_template('index.html')


@app.route("/mars", methods=["POST"])
def mars_post():
    name_receive = request.form['name_give']
    address_receive = request.form['address_give']
    size_receive = request.form['size_give']


    doc = {
        'name':name_receive,
        'address':address_receive,
        'size':size_receive
    }
    db.mars.insert_one(doc)
    
    return jsonify({'msg':'저장완료!'})


@app.route("/mars", methods=["GET"])
def mars_get():
    return jsonify({'msg':'GET 연결 완료!'})


if __name__ == '__main__':
    app.run('0.0.0.0', port=5001, debug=True)

 <script>
        $(document).ready(function () {
            show_order();
        });
        function show_order() {
            fetch('/mars').then((res) => res.json()).then((data) => {
                console.log(data)
                alert(data['msg'])
            })
        }
        function save_order() {
            let name = $('#name').val()
            let address = $('#address').val()
            let size = $('#size').val()


            let formData = new FormData();
            formData.append("name_give", name)
            formData.append("address_give", address)
            formData.append("size_give", size)


            fetch('/mars', { method: "POST", body: formData }).then((res) => res.json()).then((data) => {
                alert(data["msg"]);
            });
        }