Why my data display like question marks '? '

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PHP

MySQL

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Hello guys,
Please can you help me?
I have installed wamp server and I work on a project using bootstrap and php, the data which I insert into database is in Persian language,
but when I retrieve my records on web application it shows me it like question marks I don't know what to do pls??

Note:
// Create connection

$conn = mysqli_connect($servername, $username, $password, $dbname);
// Check connection
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

$sql = "SELECT * FROM tbl";
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) > 0) {
    // output data of each row
    while($row = mysqli_fetch_assoc($result)) {
        echo "id: " . $row["id"]. " - Name: " . $row["Name"]. "";
    }
} else {
    echo "0 results";
}

What I have tried:

I tried utf8_generial_ci,utf8_unicode_ci and utf8_persian_ci
but I have the same problem.