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: 05.05.2024 @ 20:34
Script: /register.php?sid=30a11a677c448c6ce1b68591b6e9a805
Referer: http://stc-board.de/register.php?sid=30a11a677c448c6ce1b68591b6e9a805