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 @ 18:20
Script: /board.php?boardid=4&sid=54cf777ca1297cc243c29fa561c0b9e1
Referer: http://stc-board.de/board.php?boardid=4&sid=54cf777ca1297cc243c29fa561c0b9e1