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: 09.05.2024 @ 06:27
Script: /calendar.php?sid=77d71238997edc3a06d55087c84b2544
Referer: http://www.stc-board.de/calendar.php?sid=77d71238997edc3a06d55087c84b2544