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: 04.05.2024 @ 00:10
Script: /board.php?boardid=3&sid=79cc15bb448c32020484f7851497716c
Referer: http://stc-board.de/board.php?boardid=3&sid=79cc15bb448c32020484f7851497716c