Problem; enable http2 protocol on nginx (centos 6)

I have a loadbalancer servers (nginx). The traffic comes to the loadbalance servers and forwarding them to the internal web servers (With upstream). (My internal web servers are also nginx.)

I have a config file as below. I have a lot of config files like this config file on loadbalancers. (For different subdomains.)

I want to run 80 and 443 traffic compliant with the "http2" protocol. I would like to enable the http2 protocol on my web server. I add the "http2" parameter after "listen 80" or "listen 443" command. Everything is normal until this part. (Maybe it is normal for me ..)

I have a few questions after this section.

• 1: All the articles on the internet, made for port 443. Does this have special cause and I can not do it for the 80 port?

• 2: When I add "http2" parameter to several config files in "/etc/nginx/conf.d" directory as below, the website does not open. Whenever I refresh the site, it is trying to download the page. But when I remove the http2 parameters, the problem is solved. Why is it doing this? Also, nginx configtest does not give an error.

• 3: Is there any information you can recommend to me in this regard?

#

[root@lbserver1 ~]# nginx -v

nginx version: nginx/1.12.0

[root@lbserver1 ~]# cat /etc/redhat-release

Red Hat Enterprise Linux Server release 6.7 (Santiago)

upstream k-testserver-pool  {
   # ip_hash;
   server testserver.k.local;
}

server {
   listen 80 http2;
   server_name test.www.example.com test.example.com;
   error_log /var/log/nginx/test.www.example.com.80.error.log;

   set $mobile_rewrite_status D;

   large_client_header_buffers 4 16k;

   add_header Set-Cookie "device_type=desktop; Path=/; Domain=test.www.example.com";

   location / {
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header X-Forwarded-For $remote_addr;
      proxy_set_header Host $host;
      proxy_pass http://k-testserver-pool;
      proxy_intercept_errors on;

      fastcgi_read_timeout 600;
      proxy_connect_timeout 600;
      proxy_send_timeout 600;
      proxy_read_timeout 600;
      send_timeout 600;
   }

   location ~* \.(pdf|css|js|png|gif|jpg|jpeg|ico|swf|mov|doc|pdf|xls|ppt|docx|pptx|xlsx)$ {
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header X-Forwarded-For $remote_addr;
      proxy_set_header Host $host;
      proxy_pass http://k-testserver-pool;
      expires 7d;
      add_header Cache-Control "public";
   }

   location ~ /\.ht {
      deny all;
   }
}


server {
   listen 80 http2;
   server_name test.m.example.com test.webapp.example.com;
   error_log /var/log/nginx/test.www.example.com.80.error.log;

   large_client_header_buffers 4 16k;
   add_header Set-Cookie "device_type=mobile; Path=/; Domain=test.m.example.com";

   location / {
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header X-Forwarded-For $remote_addr;
      proxy_set_header Host $host;
      proxy_pass http://k-testserver-pool;
      proxy_intercept_errors on;
      fastcgi_read_timeout 300;
   }

   location ~* \.(pdf|css|js|png|gif|jpg|jpeg|ico|swf|mov|doc|pdf|xls|ppt|docx|pptx|xlsx)$ {
      proxy_set_header X-Real-IP $remote_addr;
      proxy_set_header X-Forwarded-For $remote_addr;
      proxy_set_header Host $host;
      proxy_pass http://k-testserver-pool;
      expires 7d;
      add_header Cache-Control "public";
   }

   location ~ /\.ht {
      deny  all;
   }
}

server {
    listen 443 ssl http2;
    server_name test.www.example.com test.example.com;

    ssl on;
    ssl_certificate /etc/nginx/ssl/www.example.com.crt;
    ssl_certificate_key etc/nginx/ssl/www.example.com.key;
    ssl_ciphers  ...+3DES:DH+3DES:RSA+AES:RSA:!aNULL:!MD5:!DSS;....
    ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
    ssl_prefer_server_ciphers on;

    large_client_header_buffers 4 16k;

    location / {
       proxy_set_header Host $host;
       proxy_set_header X-Real-IP $remote_addr;
       proxy_set_header X-Forwarded-Proto https;
       proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
       proxy_pass http://k-testserver-pool;
       proxy_intercept_errors on;
       fastcgi_read_timeout 300;
    }

    location ~* \.(pdf|css|js|png|gif|jpg|jpeg|ico|swf|mov|doc|pdf|xls|ppt|docx|pptx|xlsx)$ {
       proxy_set_header X-Real-IP $remote_addr;
       proxy_set_header X-Forwarded-For $remote_addr;
       proxy_set_header Host $host;
       proxy_pass http://k-testserver-pool;
       expires 7d;
       add_header Cache-Control "public";
    }
}