Use
curl --header "Content-Type:application/octet-stream" --trace-ascii debugdump.txt --data-binary @asdf.file http://server:1234/url
Or
Install wireshark or fiddler in windows to see the http request that flows over the network.
check the headers and the values being sent. Curl adds few headers by default. These default headers may be incompatible/not-accepted by the http server you connect to in case of windows.
To modify the value of header (added by default), you can add header followed by semi-colon. For example, Content-Type; to set the value null.