How can I fix Bluetooth issues on my iPhone?

You best course of action in my experience is confirming everyone’s suspicion of Bluetooth issues. Apple Support can perform remote diagnostics, you just need to contact them using the link below. Likewise an in person session with an Apple Genius can lead to a solution as well.

Genius Bar Reservation and Apple

Support Options - Apple

It's not always the iOS update's fault!  Many things can cause phone problems.  If you tell people you think it's an iOS update, it might make it harder to fix or find a solution for the real issue.

Remember, the right question often leads to the solution!

iOS updates aim to enhance user experience, boost security, and fix bugs rather than disrupt core features. The majority of the issues after updates might stem from underlying, unmentioned factors. Updates won't typically alter personal data but may refine settings or features. Backup before major updates for safety. Review Apple's update details and backup advice for a smooth process.

Kindly consider checking your settings and addressing any device issues before attributing the issue to external factors. This could be a pure coincidence that the iOS update affected the iPhone functions.

Before initiating a standard iOS update, it's advisable to create a backup. Have you completed this step? If yes, proceed with the restoration from the backup.

See what each update does: About iOS 18 Updates, About iOS 17 Updates, About iOS 16 Updates, About iOS 15 Updates, About iOS 14 Updates, About iOS 13 Updates, About iOS 12 Updates, and so on...

I can't pinpoint the exact date I started having these problems, but it may have been with a recent update.

Never had issues before. Now, I have to stop-start Bluetooth at least once each day, or some devices will not connect (including my fairly new AirPods Pro). As a test, I did a "forget device" for the AirPods, then went through the setup process again to reconnect them. The next morning I pulled out the AirPods from the case, and they wouldn't connect automatically or by clicking the device in the Bluetooth list. Same as before. It's only by turning off Bluetooth and turning it on again that it will connect - for a while. Once I get it working, it seems to work the rest of the day. But then the next morning I have to turn off/on Bluetooth again. This is happening with at least two devices - the AirPods, and CarPlay in my 2024 vehicle.