How to fix random shutdowns on iPhone 11 after iOS 17 update?

You say the battery is fine? If you are the original owner of the phone and you've never replaced the battery, it likely is past the time to have the battery replaced. Open Settings > Battery > Battery Health. Is it at 80% or less? If yes, the battery is not fine and it needs to be replaced.

Hello~ When you say “battery is fine” what is your actual battery health? Settings > Battery > Battery Health & Charging. What’s the % shown there?

~Katana-San~

If you are still on iOS 17 update to v18 which was released way back in the fall of 2024.

My older Xr works perfectly fine on v18.4.1 so yours should too if that’s what’s holding you back.