iPhone 17 silence button is not working

You may have accidentally set the Action Button to another function, or simply disabled it. Go in and select Mute, it's the first function on the list.

You can set the Action Button here:

Settings > Action Button

You can find more useful information here:

Use and customize the Action button on iPhone - Apple Support (IS)

Hello,

Check the setting of the Action button:

Use the Action button, side button, and other controls on your iPhone - Apple Support

Note: some things are exempt and sound anyway, for example, alarms.

Good luck.

Perfect! You're welcome.