I have an 8 Plus. Got it about 2 months ago and since update 11.1.1 the home button doesn't click, it randomly shuts off 15+ times a day, it freezes every few seconds, and the speakers crackle so loud that making a phone call is impossible. I can't use the speakers for anything at all. The phone is basically useless.
Apple had me do a couple of resets but nothing helped. They deemed it a hardware malfunction. Expecting my new replacement phone this week, thank goodness. I think I am totally done with Apple though. This is my 4th iPhone in 12 months because they can't make a decent phone anymore.
If I were you, I'd return that thing and get a totally different phone before you're stuck with it like I am. My carrier had a 14 day window for returns and exchanges.