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: 09.05.2024 @ 15:02
Script: /thread.php?threadid=139&threadview=0&hilight=&hilightuser=0&sid=ba6bb83afbcdb9a578fdf6f3fa3a8533&page=39
Referer: http://stc-board.de/thread.php?threadid=139&threadview=0&hilight=&hilightuser=0&sid=ba6bb83afbcdb9a578fdf6f3fa3a8533&page=39