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: 02.05.2024 @ 13:10
Script: /register.php?sid=22a4333dbd7857e7dd0b0a3340a0b8a0
Referer: http://stc-board.de/register.php?sid=22a4333dbd7857e7dd0b0a3340a0b8a0