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: 01.05.2024 @ 15:29
Script: /board.php?boardid=5&page=1&daysprune=1000&sortfield=replycount&sortorder=ASC&sid=47a7fbd9fe7b784bcf6f3bb8037a3efb
Referer: http://www.stc-board.de/board.php?boardid=5&page=1&daysprune=1000&sortfield=replycount&sortorder=ASC&sid=47a7fbd9fe7b784bcf6f3bb8037a3efb