Data not being entered into sql database - php

Question

I have followed this tutorial https://www.youtube.com/watch?v=xb8aad4MRx8&t=225s on creating a login system and signup form on a website. I created it on my localhost and it worked perfectly. I have since tried to upload it to my website I have created a database on my server and changed the php code however no data is being entered into the database. My hosting service is 1and1 and below is the code for the code to link the database in php. Password has been changed
<?php
$host_name = 'db706265806.db.1and1.com';
$database = 'db706265806';
$user_name = 'dbo706265806';
$password = 'PASSWORD';
$conn = mysqli_connect($host_name, $user_name, $password, $database);
And this is the code for the signup form
<?php
if (isset($_POST['submit'])) {
include_once 'dbh-inc.php';
$first = mysqli_real_escape_string($conn, $_POST['first']);
$last = mysqli_real_escape_string($conn, $_POST['last']);
$email = mysqli_real_escape_string($conn, $_POST['email']);
$uid = mysqli_real_escape_string($conn, $_POST['uid']);
$pwd = mysqli_real_escape_string($conn, $_POST['pwd']);
//error handers
//check for empty fields
if (empty($first) || empty($last) || empty($email) || empty($uid) || empty($pwd)) {
header("Location: ../signup.php?signup=empty");
exit();
} else{
//check if input char are valid
if (!preg_match("/^[a-zA-Z]*$/", $first) || !preg_match("/^[a-zA-Z]*$/", $last)) {
header("Location: ../signup.php?signup=invalid");
exit();
}
else {
//check if email is valid
if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
header("Location: ../signup.php?signup=email");
exit();
} else{
$sql = "SELECT * FROM users WHERE user_uid='$uid'";
$result = mysqli_query($conn, $sql);
$resultCheck = mysqli_num_rows($result);
if ($resultCheck > 0) {
header("Location: ../signup.php?signup=usernametaken");
exit();
} else{
//hashing the password
$hashedPwd = password_hash($pwd, PASSWORD_DEFAULT);
//insert the user into db
$sql = "INSERT INTO users (user_first, user_last, user_email, user_uid, user_pwd) VALUES ('$first', '$last', '$email', '$uid', '$hashedPwd');";
$result = mysqli_query($conn, $sql);
header("Location: ../signup.php?signup=success");
exit();
}
}
}
}
} else{
header("Location: ../signup.php");
exit();
}
Any help for why the data isnt being entered would be appreciated