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: 04.05.2024 @ 22:05
Script: /thread.php?threadid=139&threadview=0&hilight=&hilightuser=0&sid=86b51f3c721c9ac9a3e0df39a371fcdd&page=1
Referer: http://stc-board.de/thread.php?threadid=139&threadview=0&hilight=&hilightuser=0&sid=86b51f3c721c9ac9a3e0df39a371fcdd&page=1