The performance of any wireless network product is dependant on the home network equipment and setup.
If you are experiencing dropouts in audio when using either AirPlay, Spotify Connect or Internet Radio, these kinds of instabilities can be caused by the bandwidth requirements of transmitting audio mixed with other data (such as downloading, etc).
Unfortunately we are unable to reduce the amount of data required to stream audio from the Internet but if you limit the amount of other data usage in the home when streaming, this will allow uninterrupted playback. This can be achieved by closing apps on your Smart device that may be using data in the background or downloading a movie from the Internet.
We would also recommend checking that you have a strong WiFi signal in your Minx Airs location, or connecting the unit directly to your router via Ethernet.