JavaScript加载函数，用于从服务器加载外部PHP文件并访问IP地址

I am testing different methods of loading a PHP file located on a separate server, I noticed that the IP address that is calling the external file is from my local IP and not the server IP. Is this always the case or is there a way to load an external PHP file from the server IP?

The load function I am currently testing is -

$("button").click(function(){
    $("#contents").load('http:server-address/test.php?id=55');
});

In the PHP file I have simple -

if(isset($_GET['id'])){
    $id = $_GET['id'];
    echo $id;
}

$ip = $_SERVER['REMOTE_ADDR'];
echo $ip;

Which everything works fine but the $ip is from my home IP address and not my .com server.. Why is this?

The reason I ask is simple, I have to create permissions for the external server to allow each accessing IP address, I only want to allow one IP which is my .com sever, it would be impossible to know everyone's IP that might access the server so I would have to allow all access which obviously I cant do.