MySQL Error 1064: You have an error in your SQL syntax near

I got this error

> You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '?, a.ip_description = ? WHERE b.id_ip_address = a.id_ip_address AND b.id_server =' at line 1

Here are my code

session_start();

include ('../connect.php');
$member_id = $_SESSION["id"];

$url = $_POST["url"]; //varchar
$list_ip_address = $_POST["list_ip_address"]; //int
$ip_description = $_POST["ip_description"]; //varchar
$dns_list = $_POST["dns_list"]; //int

$sql = "UPDATE virtual_server SET id_ip_address = ?, url = ? WHERE id_server = $member_id";
//This part right here is fine
$stsql = $mysqli->prepare($sql);
$stsql->bind_param('is', $list_ip_address, $url);

if ($stsql->execute()) {
$ip = "UPDATE list_ip_address a, virtual_server b SET a.id_dns = ?, a.ip_description = ?
WHERE b.id_ip_address = a.id_ip_address AND b.id_server = $member_id";
$stip = $mysqli->prepare($ip);
$stip->bind_param('is', $dns_list, $ip_description);
$stip->execute();
}