If you need http/2 enabled at your CPanel server, you need to do few things:
1. Install nghttp2
cd /usr/src/
wget https://github.com/nghttp2/nghttp2/releases/download/v1.15.0/nghttp2-1.15.0.tar.gz
tar -xvzf nghttp2-1.15.0.tar.gz
cd nghttp2-1.15.0
./configure --prefix=/opt/nghttp2
make
make install
echo "/opt/nghttp2/lib" >> /etc/ld.so.conf.d/custom-libs.conf
ldconfig