Let me tell you
i have now tested the VU + player
it works perfectly with my Duo 4k Black Hole with both Android tab and my mob phone using transcoding mode
(without transcoding the video is not stable and blocks the image)
Transcoding must be configured in VU + player , box configuration >> ON
(transcoding configuration and quality can be configured in the box BH image standard port for transcoding is 8002)
So the problem is with you.
But your problem is primarily the connection to the box
Did you type correctly in VU + player , box configuration
Username: root
and Your password
OpenWebInterface must be enabled on Yes
http port is standard 80 (00080 in the box)
My tab and mob phone finds automatic Duo4K
in VU + player