I am using Denon DJ prime 4 plus it self and streaming music online controller via Bluetooth no problem, but try switching to pc so i can use other program and Bluetooth disconnect and cant streaming music via Bluetooth no more. How can i fix this problem?
You can’t fix it. In standalone mode, the unit functions from an internal computer - and it’s that computer which provides wifi and bluetooth.
When you switch to controller mode, the internal computer is turned off.