My iphone 7 plus 256GB is experiencing no service or one bar or half bar. With Wi-Fi on only my internet speed went from 665mpbs down to .025mpbs on this phone. All other devices are not affected. With one bar, calls drop every two seconds. I was with Sprint for 18 years and never a problem. Then on August 26, 2021, the problems started. Sprint sent me a new T-Mobile SIM card. I installed it and still the same. I troubleshot and did all the steps. I am a web designer. Nothing. Then I decided to move to Xfinity Mobile and my phone says compatible. After the SIM card was activated, same exact problem! I have lived at this address for over a year and a half and have no problems. No one at Sprint, T Mobile, nor Xfinity can help. They do not know. For some reason, when my phone upgraded from the 12 to the 14 software, all this started. So now I have a phone that does not work. If I move around in my apartment, I lose calls. It took 7 days 15 hr days to download one audiobook that normally I can get in two seconds. Apps will not download, Speed test is less than 1 mpbs and all my other devices are running over 500-600 mpbs. If I put on cell only, no service.
I will upgrade to iphone 13 when they come out, (they do not have the black and 256 gb in stock currently) but will I have the same problem it a new phone? They say my towers are great so no one knows the problem.
BTW this phone is Model A1661. Any help would be greatly appreciated. I have spent 3 long weeks daily working on this problem and no resolution.