We used amazon S3 as upstream server. And it does not serve 'Accept-Ranges: bytes' as respond header. So the nginx proxy server will not serve range response even if the content has been completely cached on the proxy server.
We tested on a upstream server that do serve 'Accept-Ranges: bytes' as respond header. And proxy server was working proper by servering range respond.
Is that the default behavior for nginx proxy. Is there a way to overwrite it.