Found this older thread.  Would love a definitive answer.  I find JRiver to work really well as a DLNA server with a DLNA rendered (I currently use the PS Audio bridge in my direct stream DAC)...super reliable.  Does the BDP work as a renderer with JRiver as the server but playing music off the internal BDP hard drive .  I’m guessing yes.  Anyone using the BDP this way?  
Just to make it clear, I would have JRiver installed on another computer, it would just work as a DLNA server.  Ultimately, I anticipate a small nuc like machine on my network, always on and running just JRiver.