NGINX: upstream timed out (110: Connection timed out) while reading response header from upstream

I have Puma running as the upstream app server and Riak as my background db cluster. When I send a request that map-reduces a chunk of data for about 25K users and returns it from Riak to the app, I get an error in the Nginx log: > upstream timed out (110: Connection timed out) while reading > response header from upstream If I query my upstream directly without nginx proxy, with the same request, I get the required data. The Nginx timeout occurs once the proxy is put in. **nginx.conf** http { keepalive_timeout 10m; proxy_connect_timeout 600s; proxy_send_timeout 600s; proxy_read_timeout 600s; fastcgi_send_timeout 600s; fastcgi_read_timeout 600s; include /etc/nginx/sites-enabled/*.conf; } **virtual host conf** upstream ss_api { server 127.0.0.1:3000 max_fails=0 fail_timeout=600; } server { listen 81; server_name xxxxx.com; # change to match your URL location / { # match the name of upstream directive which is defined above proxy_pass http://ss_api; proxy_set_header Host $http_host; proxy_set_header X-Real-IP $remote_addr; proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; proxy_cache cloud; proxy_cache_valid 200 302 60m; proxy_cache_valid 404 1m; proxy_cache_bypass $http_authorization; proxy_cache_bypass http://ss_api/account/; add_header X-Cache-Status $upstream_cache_status; } } Nginx has a bunch of timeout directives. I don't know if I'm missing something important. Any help would be highly appreciated....