memcached – Connection Test: Failed

I tried a few while looking at topics related to memcached on this forum.

<?php
$mem = new Memcached();
$mem->addServer("ls.memcached", 11211);
//$mem->connect("127.0.0.1", 11211);
$mem->set('key1', 'This is first value', 60);
$val = $mem->get('key1');
echo "Get key1 value: " . $val ."<br />";
$mem->replace('key1', 'This is replace value', 60);
$val = $mem->get('key1');
echo "Get key1 value: " . $val . "<br />";
$arr = array('aaa', 'bbb', 'ccc', 'ddd');
$mem->set('key2', $arr, 60);
$val2 = $mem->get('key2');
echo "Get key2 value: ";
print_r($val2);
echo "<br />";
$mem->delete('key1');
$val = $mem->get('key1');
echo "Get key1 value: " . $val . "<br />";
$mem->flush();
$val2 = $mem->get('key2');
echo "Get key2 value: ";
print_r($val2);
echo "<br />";
$mem->close();
?>

I got this response

Get key1 value: This is first value
Get key1 value: This is replace value
Get key2 value: Array ( [0] => aaa [1] => bbb [2] => ccc [3] => ddd )
Get key1 value:
Get key2 value: 

Based on the search results, it is determined that this result is correct.
But even if I set the same address and same port, it comes out as faild in litespeed cache.

Of course, the php extension is marked as enabled.
Memcached Extension: Enabled
Redis Extension: Enabled