The Upsampler and App are UPnP compatible. Please make sure the Upsampler software, network firmware and dCS Vivaldi Controller App are up to date, make sure the system is connected correctly. The NAS drive must be loaded with UPnP server software as well as music and set up correctly, with UPnP Discovery Mode turned on in both the NAS and router.
A common cause of network problems is a bug in the router firmware, so please try a different router (even a $20 router should work). If the problem persists, please ask your dealer for advice.
For help resolving network problems, please consult an I.T. professional.