It has been a hot minute... I've been following this thread for over 2 months now since late September. I have an iPhone 8 plus and I had no issues with service or even had to think about issues until post upgrading to ios 14. I haven't had service since 2 before upgrading and have been using my little old iPhone SE with my sim. Weirdly enough that works no problem every time I mess with moving sim cards (on the latest ios), so I have no idea what's up. I have tried all the things (or what has felt like all the things) in this thread and to no avail. Even down to DFU mode reset. Visited the Genius Bar that is more like a Sales bar where they said that it's they can't find anything "diagnostically wrong", it's out of warranty(only 2 years old since purchase), and I'd have to pay for a new one if I want to, "but still can't guarantee that fixes the problem". Sounds suspicious enough. The person also mentioned they have been receiving this problem for months too, and I'm like "?!?!?!? shouldn't apple be aware of this ?!?!". I'm writing moreso for the people just following along like I was and wanted to say you're not alone. But maybe if we keep this thread going and have more people chime in this can be pushed up the priority list for Apple. Someone has to know this is a problem and maybe just not enough media to take action, or potentially worse... our phones are bricked and they don't want to admit it. Here's to hoping the former and an ios update comes out that resolves it. Good luck with everyone and this really makes me not want to buy another iphone ever and switch to another brand, but thinking about coughing up the money makes me sick when us as users are not at fault.