I’m trying to connect my windows machine with xampp, using php with PDO, to a server on the local network (Linux)

<?php

$dbname = "DBNAME";
$user = "USERNAME";
$pass = "PASSWORD";

try{
    $conn = new PDO("mysql:host=HOST;port=PORT;dbname=" . $dbname, $user, $pass);
    echo "Conexão com o banco de dados realizada com sucesso";
} catch(PDOException $err) {
    echo "Erro ao conectar ao banco: ". $err->getMessage();
}
?>

This gives me an error:
SQLSTATE[HY000] [2002] No connection could be made because the target machine was selected

How to solve the problem?