با سلام
بله روی cpanel هستش
طبق اموزش های سایت whmcs گفته شده که این ارور مربوط به بسته بودن پورت ها هستش
اما مدیر سرور میگه که این پورت ها بازن
Server Command Error - Curl Error - Couldn't connect to host (7)

Getting this error means that you have a firewall on your server blocking the connection. The port being used depends upon the module in use but for cPanel it would be 2086/2087, Plesk 8443, DirectAdmin 2222, etc... open for inbound and outbound connections on both the server WHMCS is installed on and the remote server being connected to. Please contact your server admin/hosting provider to open those ports.