Adding proxy_max_temp_file_size 0 to nginx config.

Explanation:
When proxying an HTTP request, nginx first fills up the memory buffers (set by proxy_buffer_size and proxy_buffers).
When these are full, it then writes them to a temporary file in batches of proxy_temp_file_write_size until it reaches proxy_max_temp_file_size.
When proxy_max_temp_file_size is not set, and a very large file is being served, it reaches the maximum of 1GB, and nginx begins to behave weirdly.

setup/start/nginx/appconfig.ejs

@@ -76,6 +76,9 @@ server {
         proxy_buffers           4 256k;
         proxy_busy_buffers_size 256k;
 
+        # No buffering to temp files, it fails for large downloads
+        proxy_max_temp_file_size 0;
+
         # Disable check to allow unlimited body sizes
         client_max_body_size 0;