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 @ 19:38
Script: /register.php?sid=2b1d19c9d0c6500213ef1c3281eb324f
Referer: http://stc-board.de/register.php?sid=2b1d19c9d0c6500213ef1c3281eb324f