SQL-DATABASE ERROR

Database error in WoltLab Burning Board (): Link-ID == false, connect failed
mysql error: Can't connect to MySQL server on 'rdbms.webmailer.de' (146)
mysql error number: 2003
mysql version: unknown
php version: 5.6.40
Date: 24.10.2019 @ 02:30
Script: /wbb/board.php?boardid=52
Referer: