SQL-DATABASE ERROR

Database error in WoltLab Burning Board (2.1.5): Link-ID == false, connect failed
mysql error: Unknown MySQL server host 'db08.kundenserver.de' (0)
mysql error number: 2005
mysql version: unknown
php version: 4.4.9
Date: 19.04.2019 @ 00:42
Script: /lexikon/escorial.lex.php
Referer: