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: 10.05.2024 @ 09:14
Script: /register.php?sid=56b16c85f102c5d54a6280b0bc76bb1e
Referer: http://stc-board.de/register.php?sid=56b16c85f102c5d54a6280b0bc76bb1e