SQL-DATABASE ERROR

Database error in WoltLab Burning Board (): Link-ID == false, connect failed
mysql error: Connection refused
mysql error number: 2002
mysql version: unknown
php version: 5.6.40-57+0~20211119.60+debian9~1.gbp8a9bd1
Date: 08.05.2024 @ 00:18
Script: /board.php?boardid=3&sid=a3dcc131867545441c4c9c9d75f51eba
Referer: http://stc-board.de/board.php?boardid=3&sid=a3dcc131867545441c4c9c9d75f51eba