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 @ 01:52
Script: /calendar.php?action=eventcalendar&sid=717db4badb60fe5e8e174e12bfe0f52d
Referer: http://stc-board.de/calendar.php?action=eventcalendar&sid=717db4badb60fe5e8e174e12bfe0f52d