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: 03.05.2024 @ 15:31
Script: /board.php?boardid=4&daysprune=1000&sortfield=topic&sortorder=ASC&sid=c2fa6dc1817c2490e1f31c0e6d74d1fa&page=7
Referer: http://stc-board.de/board.php?boardid=4&daysprune=1000&sortfield=topic&sortorder=ASC&sid=c2fa6dc1817c2490e1f31c0e6d74d1fa&page=7