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: 06.05.2024 @ 14:06
Script: /board.php?boardid=39&sid=664ebb9361ad2d997ee9783d6c02d89b
Referer: http://www.stc-board.de/board.php?boardid=39&sid=664ebb9361ad2d997ee9783d6c02d89b