ChatGPT answer prompt here https://datafit.ai/prompt/21950#

Here's how to,

updating the API URL in your client-side code is necessary to ensure that your app makes API requests to the correct server. However, you may also need to update the server-side configuration to match the IP address or domain name changes

mongoose
  .connect("mongodb://yourIpAddress/yourprojectnameinmongodb", {
    useNewUrlParser: true,
    useUnifiedTopology: true,
  })
  .then(() = {
    console.log("Connected to Mongo Db");
  })
  .catch((err) = {
    console.log("Error connecting to MongoDb", err);
  });

if doesn't work, in place of ipaddress add 127.0.0.1:27017 it should probably work!

then ...

app.listen(port, "IpAdressofyourpc", () = {
  console.log("Server is running on http://youripadress");
});

then in the frontend-part while initialising the function you need to make the change

  axios
       .post("http://youripadress:8000/register", user)

To get the ip adress of your sytem
Mac = ipconfig getifaddr en0
Windows = ipconfig