Enable HTTP/2

HTTP/2 is the latest revision of the HyperText Transfer Protocol or HTTP [01], which is used by browsers to communicate with web servers. Derived from the older SPDY [02] protocol, HTTP/2 is the first new version of HTTP

To enable HTTP/2, you need to define it on listen ports.

Select the configuration of your website,
Select your already defined port or click on “New Entry” button to create a new port
Turn on the SSL Encryption option
Turn on the HTTP/2 option.