use Symfony\Component\Ldap\Ldap;

$ldap = Ldap::create('ext_ldap', ['host' => 'ldap.service.address.ip', 'port' => '389']);

$ldap->bind('user@dn', 'password');

# fail
PHP Warning:  ldap_bind(): Unable to bind to server: Can't contact LDAP server in /var/www/vendor/symfony/ldap/Adapter/ExtLdap/Connection.php on line 60
Symfony/Component/Ldap/Exception/ConnectionException with message 'Can't contact LDAP server'

# success
null