iPhone connection problems

I have an iPhone 13 locked AT&T ever since I update to

iOS 17.4.1 i'm having problem with connections like LTE missed phone calls missed text messages I spoke to the AT&T carrier rep highest level customer service I have been on the phone with them for almost 2 hours and they tried everything they put me a new Sim card and they activate the eSIM nothing is working talk to my phone to the Apple Store and those you know what they want to blame my carrier the new software update is having multiple problems I have missed a important phone calls text messages and I honestly don't know what to do connect my phone to iTunes data factory reset still having problems how can I fix this and I'm still stuck with a contract with AT&T I spoke to the highest level tech-support at AT&T they were nice enough to give me a $45 credit but still does not fix the problem is anyone else still having the same issue