The sound on the iPad turns off periodically. What to do, it works after reboot

We can better help with more details in the limited setting. As your fellow end users, we can neither see nor remotely access your iPad to determine hardware details? We can only get that from you.

What iPad model? Its iPadOS version? How long have you owned/used it? This link may help:

Identify your iPad model - Apple Support

The very basic info you posted suggests a failing battery. Once we know more about your iPad and OS version, we can better advise you on how to approach this.

At this point, all we can say is "have Apple evaluate."