query result took from wordpress database showing as question marks

Question

I have saved Telugu language content in the database with utf8mb4_unicode_ci collation, and I am trying to extract that information from a different place (Not WordPress environment) everything ok but Telugu characters are showing as question marks.

this is the content stored in the database. ఆ ఒక్క మాట తో కంపెనీ సర్వ నాశనం | #OURMINE | #VEVO This is the text i am getting. ? ???? ??? ?? ?????? ???? ????? | #OurMine | #Vevo

Code i used to get the information.

<?php
$con=mysqli_connect("localhost","db","pw","db");
    mysqli_set_charset('utf8', $con);
 // Check connection 
   if (mysqli_connect_errno())
 {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
 }
 error_reporting(E_ALL ^ E_NOTICE);
 $query = "SELECT * FROM TT_posts WHERE post_status='publish' AND ping_status='open'";
 mysqli_set_charset('utf8', $query);
 $result = $con->query($query);
while ($row = $result->fetch_assoc())   {
    ?>
<?php  
  $image = "SELECT * FROM TT_posts WHERE post_parent='$row[ID]' AND 
post_title='FEATURED' AND post_type='attachment'";
  $result1 = $con->query($image); 
    while ($row1 = $result1->fetch_assoc())
    $img = $row1[guid]; 
 ?>

<div class="featured-thumbnail"><?php echo '<img src="'.$img.'">';?></div>
<header>
<h3 class="featured-category-title"><?php echo $row[post_title];?></h3>
</header>
<?php } ?>

I don't know where i am wrong.