A long time ago I was repairing my dad's camera, I found an article describing the exact fault & a link to how to fix it, but the link was dead.
Used the wayback machine to find a text only copy of the fix (no pictures) which was enough.
Was immensely proud that someone had had the idea to invent the IA & have been recommending it ever since.
The only paid app I've got is Sound Profile. Puts the phone on quiet (except for family) at night, or silent (with auto resume to normal) in meetings. It's on my & spouse's phones.