Now with time, the buttons of your iPhone 6s may face wear and tear and may cease to function properly. The most common issues faced regarding the buttons of smartphones are...

• The Sound doesn’t increase/decrease when I press the volume up or down key.
• The buttons are stuck and can’t be pressed
• The switch doesn’t work/automatically switch between ringer and silent mode
• Home button doesn’t work/unlock the phone.

These are the most common issues regarding the physical buttons in the smartphone. However, Apple recommends restarting the device and update the iOS in this case. And if it still does not fix the issues, it needs to be getting looked at by professionals. iPhone recommends using Assistive touch for the longevity of the physical buttons of the iPhone 6s.