My web architecture is:
nginx(reverse proxy) -> nginx + php-fpm

It's normal when i curl it on pc(linux shell and pc Browser).
This's nginx(reverse proxy) access.log:
117.136.40.0 - - [06/Jul/2016:17:38:31 +0800] "GET /a.php HTTP/1.1" 200 66 .......

It's not normal when i access it on my phone(android Browser). But it will be normal sometimes.
117.136.40.0 - - [06/Jul/2016:17:40:09 +0800] "GET /a.php HTTP/1.1" 499 0 .......
117.136.40.0 - - [06/Jul/2016:17:40:18 +0800] "GET /a.php HTTP/1.1" 200 66 ......

If I set "proxy_ignore_client_abort on" on nginx's config. Access_log will be this:
117.136.40.0 - - [06/Jul/2016:17:40:18 +0800] "GET /a.php HTTP/1.1" 200 0 ......

Please help me!