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: 02.05.2024 @ 23:49
Script: /calendar.php?sid=055dc123918045f9b95f2a17dd3a82d7
Referer: http://stc-board.de/calendar.php?sid=055dc123918045f9b95f2a17dd3a82d7