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: 07.05.2024 @ 00:03
Script: /calendar.php?sid=5e882f721145955c38ccbb4f5b9267b0
Referer: http://stc-board.de/calendar.php?sid=5e882f721145955c38ccbb4f5b9267b0