connection failed in App\Model\Db\Db::getInstance

SQLSTATE[HY000] [2002] Connection refused

Fatal error: Uncaught TypeError: Cannot assign null to property App\Model\Db\Form::$pdo of type PDO in /home/amotsh6v/public_html/Model/Db/Form.php:30 Stack trace: #0 /home/amotsh6v/public_html/Model/Articles.php(174): App\Model\Db\Form->__construct('articles') #1 /home/amotsh6v/public_html/controller/articlesController.php(53): App\Model\Articles->rendeThemesList(false) #2 /home/amotsh6v/public_html/application/router.class.php(85): articlesController->index() #3 /home/amotsh6v/public_html/index.php(35): router->loader() #4 {main} thrown in /home/amotsh6v/public_html/Model/Db/Form.php on line 30