Bose SoundTouch, NAS, and AirPort Extreme

Dear all,

I have connected a Bose SoundTouch to my AirPort Extreme (older version) via Wi-Fi: to the same network it is connected also a Synology NAS on which I have downloaded my audio files. The problem is that internet connection stops working several times a day and then music stops as well. I am wondering if there is any network setup that I can deploy to prevent this annoyance from happening. Can I setup my intranet so that it does not depend on the availability of an internet connection?

Thanks for helping!

Valerio