PHP支持希伯来语

the below string arrive to the server in Gibberish instead of Hebrew, please help, this is how my code look like (i'm getting long string and insert every part to the db)? For example the name insert as ; לירן מה קורה

        <?php

    $data_to_server = $_POST['data_to_server'];
    $length = $_POST['length'];

    $servername = "";
    $username = "";
    $password = "";
    $dbname = "";

    $conn = new mysqli($servername, $username, $password, $dbname);

    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    } 

    $users_list = $data_to_server;

    $users_list = str_replace(array("phone:","name:","event_id:"),array("","",""),$users_list);

    //$users_num = 4;
    $sql_str = "INSERT INTO invite_list (phone,name,event_id) VALUES ";


    for ($i=0; $i<$length; $i++){

      $temp_list = "";
      $temp_list = substr($users_list, 0, strpos($users_list, '/'));
      $users_list = str_replace($temp_list."/","",$users_list);
      $sql_str = $sql_str . "(" . $temp_list;


      if ($i < $length-1)
          $sql_str = $sql_str . "),";
      else
          $sql_str = $sql_str . ");";
    }

    $sql = $sql_str;

if ($conn->query($sql) === TRUE) {
    echo json_encode(array("Result"=>"success"));

} else {
    echo json_encode(array("Result"=>"failed"));
}

$conn->close();

It may not be PHP that is having the issue; also verify that MySQL is using a UTF8 connection and that the tables (and columns) are in UTF8.