I switched run nginx/1.9.12 (from nginx.org) on my web server to gain http2 features under ssl.
What I noticed in /etc/nginx/nginx.conf file nginx executes as user nginx.
Here is how I installed that:
apt-get install nginx;
With HTTP2 there is only one TCP connection to the web server to load the full page.
Before any action, first save your last configuration files for Nginx, that are in /etc/nginx