Problem with memcached and SASL authentication

Hello, we’ve recently moved our website to a new hosting

The new hosting has the same configuration of the older but, on this one, memcached needs SASL authentication

Currently we see this error

The following memcached servers are not responding or not running:

    Database Cache: 127.0.0.1:11211.
    Object Cache: 127.0.0.1:11211.

This message will automatically disappear once the issue is resolved.

But when adding the SASL authentication the warning won’t disappear and the site becomes really slow

The weird thing if we do a basic connection directly with PHP, it works

<?php
    // Connection
    $m = new Memcached('test_pool');
    $m->addServer('127.0.0.1', 11211);

    // Add configuration
    $m->setOption(Memcached::OPT_BINARY_PROTOCOL, true);
    $m->setSaslAuthData("#", "#");

    // Get stats
    echo '<pre>';
    print_r($m->getStats());
    echo '</pre>';

    $m->set('test', 'this is a test');

    var_dump($m->get('test'));
?>

Is anything we may be missing?

Server is on PHP 7.4 as the website is old and can’t update right now, W3C Total Cache is on the last version available

Thanks for your help