HTTP/2 is an HTTP version which makes applications faster, simpler, and more robust in comparison with HTTP/1. To be able to use HTTP/2 you need to set up the connection through HTTPS. To make your website support HTTPS, enable the option Secure connection (SSL)  on the website creation or edit form. For more information refer to the article Add a WWW-domain.

HTTP/2 is supported only in Nginx on CentOS 7. Read more in Web-servers. 

Complete the following steps:

  1. Navigate to Cluster settings → Policy.
  2. Check the Enable HTTP/2 box.
  3. HTTP/2 will be enabled for all the WWW-domains wit the Secure connection (SSL) activated.