![cannot connect to the zcs upstream server. cannot connect to the zcs upstream server.](https://pbs.twimg.com/media/ErJiGIGXcAAK2g3.jpg)
![cannot connect to the zcs upstream server. cannot connect to the zcs upstream server.](http://3.bp.blogspot.com/-JZYqchoFPIE/VackOzKVQVI/AAAAAAAADG0/waHgX1uG5po/s1600/MyPBX_U100_01.gif)
The problem I have is that NGINX closes the TCP connection to any upstream server that returns a 404. The server on which the content is found has successfully established a connection using the keepalive / HTTP 1.1 method. This works well, however, there is a delay in "fishing through" any upstream servers that don't have the content to find the correct one due to TCP overhead. The content requested is only on one of these servers, so I keep "trying" until I find the content, or die after I've exhausted all upstreams. I have an NGINX upstream definition that involves rotation through several servers to find content. fstack-protector-strong -Wformat -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fPIC' -with-ld-opt='-Wl,-z,relro -Wl,-z,now -Wl,-as-needed -pie' Linux srv001b-media-01 5.4.0-72-generic #80-Ubuntu SMP Mon Apr 12 17:35: x86_64 GNU/LinuxĬonfigure arguments: -prefix=/etc/nginx -sbin-path=/usr/sbin/nginx -modules-path=/usr/lib/nginx/modules -conf-path=/etc/nginx/nf -error-log-path=/var/log/nginx/error.log -http-log-path=/var/log/nginx/access.log -pid-path=/var/run/nginx.pid -lock-path=/var/run/nginx.lock -http-client-body-temp-path=/var/cache/nginx/client_temp -http-proxy-temp-path=/var/cache/nginx/proxy_temp -http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp -http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp -http-scgi-temp-path=/var/cache/nginx/scgi_temp -user=nginx -group=nginx -with-compat -with-file-aio -with-threads -with-http_addition_module -with-http_auth_request_module -with-http_dav_module -with-http_flv_module -with-http_gunzip_module -with-http_gzip_static_module -with-http_mp4_module -with-http_random_index_module -with-http_realip_module -with-http_secure_link_module -with-http_slice_module -with-http_ssl_module -with-http_stub_status_module -with-http_sub_module -with-http_v2_module -with-mail -with-mail_ssl_module -with-stream -with-stream_realip_module -with-stream_ssl_module -with-stream_ssl_preread_module -with-cc-opt='-g -O2 -fdebug-prefix-map=/data/builder/debuild/nginx-1.20.0/debian/debuild-base/nginx-1.20.0=. Upstream Keepalive - TCP connection to the upstream closes Reported by: