<?php
$servername = "link do server";
$username = "usuario";
$password = "senha";

$conn = mysqli_connect($servername, $username, $password);

if (!$conn) {
   die("Connection failed: " . mysqli_connect_error());
}
echo "Connected successfully";
?>

echo $conn = mysqli_connect("127.0.0.1", "usuario", "senha", "nome db") or die("Connection failed: " . mysqli_connect_error($conn));

echo $conn = mysqli_connect("localhost", "usuario", "senha", "nome db") or die("Connection failed: " . mysqli_connect_error($conn));