PHP Connection issues related to the LoginPHPMySQL

[infyProductions]

I had a lot of database connection issues while trying out this project. After I started XAMMP (with Apache and MySQL only) and trying to run the application. The android part of the tutorial works but when I tried to connect my phone (as a test device) to the webserver hosted on my machine, it returns an error pertaining to "Unable to retrieve any data from server".

I tried browsing on http://localhost/test_android/index.php when it returned an error like:
Fatal error: Uncaught ArgumentCountError: mysqli_connect_errno() expects exactly 0 arguments, 1 given in D:\XAMPP\htdocs\test_android\db-connect.php:13 Stack trace: #0 D:\XAMPP\htdocs\test_android\db-connect.php(13): mysqli_connect_errno(Object(mysqli)) #1 D:\XAMPP\htdocs\test_android\user.php(12): DbConnect->__construct() #2 D:\XAMPP\htdocs\test_android\index.php(31): User->__construct() #3 {main} thrown in D:\XAMPP\htdocs\test_android\db-connect.php on line 13

I also checked the logcat logs of the app and it returned a similar error like the one on the top:
E/API123: 200
D/API123:

Fatal error: Uncaught ArgumentCountError: mysqli_connect_errno() expects exactly 0 arguments, 1 given in D:\XAMPP\htdocs\test_android\db-connect.php:13
Stack trace:
#0 D:\XAMPP\htdocs\test_android\db-connect.php(13): mysqli_connect_errno(Object(mysqli))
#1 D:\XAMPP\htdocs\test_android\user.php(12): DbConnect->__construct()
#2 D:\XAMPP\htdocs\test_android\index.php(31): User->__construct()
#3 {main}
thrown in D:\XAMPP\htdocs\test_android\db-connect.php on line 13

E/JSON Parser: Error parsing data org.json.JSONException: Value <br of type java.lang.String cannot be converted to JSONObject

I checked the questionable line and it looks like this:
Line 13: if (mysqli_connect_errno($this->connect)){
Line 14: echo "Unable to connect to MySQL Database: " . mysqli_connect_error();
Line 15: }

I used the default credentials on XAMMP with the DB_HOST set as localhost.