I have got Sim Failure error after upgrading to iOS 17.5.1

It's definitely not coincidental.

I have iPhone 13 Pro and started getting SIM failure after 17.5.1 update.

And there are a lot others who are facing this same issue.

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! Please look in the right direction.

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 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...

Happened to mine my wife's and my parents iPhone 13 pros within hours of updating to 17.5.1.

Check with apple support - esim wont help either if the whole SIM module isn't loading. They can run an analysis remotely if you are in a WLAN.

Got a date at the apple store in 2 days - maybe we will know more by then. To me it sounds like a bug and not hardware failure because I know it worked EXACTLY until the reboot.

Nothing you can do other than going to Apple right now.