Ringer and alerts volume randomly goes to zero

A couple of times a year, my timer and alarm alerts no longer work.

When I go into SETTINGS>SOUND & HAPTICS>RINGER AND ALERTS I find the slider all the way to the left which is to say zero volume. I note that this slider can also be controlled by the physical UP & DOWN buttons on the left side of the phone, so perhaps I hit the down button inadvertently when fighting some other issue. Suggestion: separate timer and alarm volume controls from the external buttons. Bury them somewhere where they are not easily turned off. Of what use is a silent alarm clock anyway?