SQL-DATABASE ERROR

Database error in WoltLab Burning Board: Link-ID == false, connect failed
mysql error: Unknown MySQL server host 'mis47.de' (110)
mysql error number: 2005
Date: 27.07.2021 @ 13:16
Script: /register.php?sid=f37aea7f33ad5f08d32a13090c5b8825
Referer: