Using Memcached as Session Handler in CodeIgniter randomly gives error

Question

To work with sessions via Memcached in CodeIgniter 3, should I also configure PHP to use Memcached or just configure in CodeIgniter is that enough?

My project in CodeIgniter 3 is used with several requests via AJAX, and I've been getting the error below a lot for some random requests:

session_start(): Failed to read session data: user (path: 192.168.0.50:11211)

I will got one external servers on the same network to store all sessions. This is my session config (CodeIgniter):

$config['sess_driver']             = 'memcached';
$config['sess_cookie_name']        = 'ci_session';
$config['sess_expiration']         = 0;
$config['sess_save_path']          = '192.168.0.50:11211'; /*Without TCP*/
$config['sess_match_ip']           = FALSE;
$config['sess_time_to_update']     = 300000;
$config['sess_regenerate_destroy'] = FALSE;

I even tried creating a PHP script with a 1000 iteration loop with session_start() and session_destroy(), but I couldn't reproduce this error. It only occurs in CodeIgniter.

On the server that I do the tests, PHP 7.4 is configured so that the session_handler is memcached.

We've also tried modifying the php/memcached configuration values ​​(based on other questions on StackOverflow) and it didn't work.

memcached.sess_lock_retries = 10 (default=5)
memcached.sess_lock_wait_min = 150 (default)
memcached.sess_lock_wait_max = 2000 (default=150)