The network connectivity or audio dropout issues may be due to interference from other devices in the environment.
To resolve this issue, toggle the Channel switch (RF Bands) on the back of both the transmitter (connected to the computer) and receiver (connected to the audio system) to another channel (If in position 1, change to position 2 or 3).
Note: The channel number (position) should be the same on both transmitter and receiver.
If the issue persists, place the transmitter and receiver next to each other (within few centimeters), temporarily turn off all other Bluetooth or wireless signals nearby, and try again.
Also, try reinstalling the Wireless USB DAC drivers.
When the above methods do not help, please carry Wireless USB DAC 1/2 to your nearest NAD Distributor for further evaluation.