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: 08.05.2024 @ 08:39
Script: /usercp.php?action=addsubscription&threadid=793&sid=05fe213950d01e3cda6e96e8da4e644e
Referer: http://stc-board.de/usercp.php?action=addsubscription&threadid=793&sid=05fe213950d01e3cda6e96e8da4e644e