Roku Media Player so SLOW to load library via DLNA

Hi - I have a Roku Ultra. All works great but the Roku Media Player just has a spinning wheel forever (30+ minutes).

I use PlayOn on a pretty high horsepower Windows 10 system.

It seems to me the Roku is scanning the library before it displays selections. If I access the same DLNA/PlayOn server using VLC on my iPhone - everything is pretty instantaneous.

Any thoughts? Is there a setting I can tweak? The Roku and iPhone are both on the same 5ghz wifi network. The Windows 10 machine has a 1G ethernet connection to the router.