ERROR [2] mysqli_connect(): (HY000/2002): Connection refused

  Fatal error in line 8 of file /var/www/vhosts/lasi-italia.com/httpdocs/backoffice/inc_mysql_lib.php, PHP 5.6.40-55+0~20211023.59+debian10~1.gbp650f36 (Linux)

This is the debug trace

Error: "mysqli_connect(): (HY000/2002): Connection refused" (error #2).
[PHP Error 2024/07/27 12:27:35]Backtrace:
[PHP Error 2024/07/27 12:27:35]  0: myErrorHandler 
[PHP Error 2024/07/27 12:27:35]  1: mysqli_connect (line 8 in /var/www/vhosts/lasi-italia.com/httpdocs/backoffice/inc_mysql_lib.php)
[PHP Error 2024/07/27 12:27:35]  2: db_connect (line 57 in /var/www/vhosts/lasi-italia.com/httpdocs/backoffice/inc_conn.php)
[PHP Error 2024/07/27 12:27:35]  3: include_once (line 2 in /var/www/vhosts/lasi-italia.com/httpdocs/rewrite.php)
[PHP Error 2024/07/27 12:27:35]Variables in myErrorHandler ():
[PHP Error 2024/07/27 12:27:35]Client IP: 3.149.238.239
Aborting...