Not 100% sure, because you did not provide the code or sample stream for testing, but your HTTP range request processing has been violated.
In the request of your example, the client sends Range: bytes=0-and your server responds with a 1MiB response:
Content-Length: 1048576 (aka. 1 MiB)Content-Range: 0-1048575/...
, ! bytes=0-, 0 (. http 1.1 RFC), Range. (IIRC, Firefox - Range: bytes=0- , ).
, Content-Length, (Firefox) , 1 , . , 1 MiB 1:06 .
PS: Content-Duration (, RFC 3803) - , .