Database error in vBulletin :

mysql_connect(): Can't connect to MySQL server on 'mysqlucoolbbsmaster' (104)
/data/product/ucool/production/bbs/a/includes/class_core.php on line 317

MySQL Error   : 
Error Number  : 
Request Date  : Wednesday, November 29th 2023 @ 07:27:19 AM
Error Date    : Wednesday, November 29th 2023 @ 07:27:25 AM
Script        : http://forum.ucool.com/calendar.php
Referrer      : 
IP Address    : 44.212.96.86
Username      : 
Classname     : vB_Database
MySQL Version :