One of the following is the problem:
Your host has disabled cURL and fopen() URL wrappers for the PHP CLI binary. One of them must be enabled for Joomla! to fetch the update information.
Your host has a firewall which prevents CLI applications from accessing the web. They need to open TCP port 80 to cdn.akeebabackup.com and port 443 to www.akeebabackup.com.
Please note that the PHP CLI is a different executable than the version of PHP used on your web server to render .php pages, with a different configuration.
Nicholas K. Dionysopoulos
Lead Developer and Director
π¬π·Greek: native π¬π§English: excellent π«π·French: basic β’ π My time zone is Europe / Athens
Please keep in mind my timezone and cultural differences when reading my replies. Thank you!