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 @ 15:38
Script: /register.php?sid=9a41fe63a4a05b52bedd5ae4359e7fcc
Referer: http://stc-board.de/register.php?sid=9a41fe63a4a05b52bedd5ae4359e7fcc