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 @ 00:53
Script: /board.php?boardid=18&sid=1a6474ddd7f76cc7d5d3d3a6bf99e3d1
Referer: http://stc-board.de/board.php?boardid=18&sid=1a6474ddd7f76cc7d5d3d3a6bf99e3d1