What could be the problem when connecting via PDO with SSL, with SQLSTATE[HY000] [2002] error?

Question

PHP

Good time of the year!
When trying to connect to a remote server via PDO with SSL like this

try{
        $db = new PDO("mysql:host=db.server.ru;dbname=testbase",
                      'ssluser',
                      'pass',
                      [
                          PDO::MYSQL_ATTR_SSL_KEY  => VARS . '/certs/client-key.pem',
                          PDO::MYSQL_ATTR_SSL_CERT => VARS . '/certs/client-cert.pem',
                          PDO::MYSQL_ATTR_SSL_CA   => VARS . '/certs/ca.pem'
                      ]
        );
} catch(PDOException $ex){
    var_dump($ex->getMessage());
    echo "\r\n";
}

I get SQLSTATE[HY000] [2002] error with no other text. Most likely there Connection refused.
On the server is mariadb.
Generated certificates like this . Common names are different for certificates.
When executed on the server where the script is running with an error, the commands in the console

mysql -h db.server.ru -ussluser -p --ssl-ca=/var/www/.../var/certs/ca.pem --ssl-cert=/var/www/.../var/certs/client-cert.pem --ssl-key=/var/www/.../var/certs/client-key.pem

connection is normal, no errors.
The directory with certificates looks like this

drwxrwxrwx  2 apache apache 4096 Mar 15 13:40 .
drwxrwxrwx 11 root   root   4096 Mar 15 13:40 ..
-rwxrwxrwx  1 apache apache 1679 Mar 16 18:14 ca-key.pem
-rwxrwxrwx  1 apache apache 1285 Mar 16 18:14 ca.pem
-rwxrwxrwx  1 apache apache 1155 Mar 16 18:14 client-cert.pem
-rwxrwxrwx  1 apache apache 1675 Mar 16 18:14 client-key.pem
-rwxrwxrwx  1 apache apache  985 Mar 16 18:14 client-req.pem
-rwxrwxrwx  1 apache apache 1155 Mar 16 18:14 server-cert.pem
-rwxrwxrwx  1 apache apache 1679 Mar 16 18:14 server-key.pem
-rwxrwxrwx  1 apache apache  985 Mar 16 18:14 server-req.pem

Muscle logs on this connection show nothing. The logs are: log_error and general_log_file.
Centos system. There is nothing in the messages and secure logs about this either.