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: 11.05.2024 @ 00:00
Script: /register.php?sid=f6afa50fa7e3877c6bd6b4a3f2f7a959
Referer: http://www.stc-board.de/register.php?sid=f6afa50fa7e3877c6bd6b4a3f2f7a959