Tente fazer o seguinte: remova proxy_cache nginx-cache;
, remova proxy_buffering Off;
e substitua proxy.conf
conteúdo pelos seguintes valores:
proxy_buffers 32 4m;
proxy_busy_buffers_size 25m;
proxy_buffer_size 512k;
proxy_ignore_headers "Cache-Control" "Expires";
proxy_max_temp_file_size 0;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
client_max_body_size 1024m;
client_body_buffer_size 4m;
proxy_connect_timeout 300;
proxy_read_timeout 300;
proxy_send_timeout 300;
proxy_intercept_errors off;