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: 28.04.2024 @ 10:03
Script: /board.php?boardid=18&sid=a1cb03997350aa8f477dcbfc0158ea4f
Referer: http://stc-board.de/board.php?boardid=18&sid=a1cb03997350aa8f477dcbfc0158ea4f