This is and was my very first iPhone. As I decided to give it a try after over 10 years with Android. I have never had such a slow and steady failure like this before. Ever since mid July I would completely lose cellular service for 3 or more hours every week. It then happened every couple of days and the it happened every day, so I had to use my S9 Plus as a backup. No amount of updates would work, iTunes restore and DFU would come back with errors and factory resetting inside ios lead to this. Warranty expired in June and I dont have applecare. I looked up what this image meant and it came up as baseband failure, a hardware issue. I wish you guys well but I don’t think I am coming back to iphone anytime soon.
It’s a hardware problem. Bad baseband. If you look up I’ve got a comment laughing at all the comments like “I’ve had iPhone since 3gs no issues” and explaining it not in depth, then I have another that goes in depth on the issue. Anyways if you don’t believe me, here’s a bad baseband 12 for example.
https://preview.redd.it/8utt6bpxb1xb1.jpeg?width=2268&format=pjpg&auto=webp&s=06dcaa4d6b7e2f05c69dcccfdd0749f817535acc