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: 05.05.2024 @ 11:14
Script: /board.php?boardid=5&daysprune=1000&sortfield=lastposttime&sortorder=ASC&sid=3e92ea432f057336379b94a44b035532&page=3
Referer: http://stc-board.de/board.php?boardid=5&daysprune=1000&sortfield=lastposttime&sortorder=ASC&sid=3e92ea432f057336379b94a44b035532&page=3