Wifi to 5G Conversion Connectivity Issues

I'm frustrated and feeling helpless with my iPhone 12 Pro Max and AT&T 5G. This winter I would have had the phone for a year and since that time I have experienced nonstop issues with how my phone behaves when connecting to 5g when I leave a wifi connection. Is anyone else experiencing the below issues or have a fix that I, AT&T or Apple haven't tried already?

The Issue

When at home, I'm typically on my wifi and everything is fine. When I leave my house, my phone struggles to switch over to the cellular network to allow data services. I can make a call, but I can't stream music or browse the internet or use any app that requires data (including iMessage). Regular texts that are not iMessage work just fine. I live in St. Pete FL and the 5g network is everywhere so it's not a coverage issue. Sometimes when it does finally connect, its intermittent. Meaning I can be on a walk streaming music (as an example) and then it just stops. I try pulling up a webpage and it won't load. Minutes pass by and then I'm able to connect. Sometimes its good after that and then other times it just comes and goes.

I've discovered that if I put the phone in airplane mode for a few seconds and then toggle it off while turning off the wifi, most of the time that allows the phone to connect to 5g. If I do the same thing, but don't turn off the wifi, I don't have as much luck. If I just turn off the wifi, sometimes I'll connect to 5g but I have better luck doing the airplane mode (on and off) and then shutting off the wifi. I started doing this wifi and airplane mode thing thinking that maybe the phone was trying to connect to other nearby wifi signals while I'm out and about and it was just getting stuck (I walk around a lot where shops and retail stores are located).

What's been done to assess and fix my problem?

• AT&T was no help. They had me reset network settings. Swapped out my SIM. Blamed Apple.
• Several hours with Apple support...
• Resetting network settings - works initially but the problem starts in a matter of hours.
• Restoring my phone - works initially but the problem starts in a matter of hours.
• Apple sent me a new phone but still having the same issue.
• Got another new phone because of another situation and it too is having the issue.
• Trying different 5G settings (Auto vs. Always on) and this doesn't help.
• Trying LTE. There is some improvement but this not acceptable. I paid for a 5g phone and service and it should work!
• Trying different wifi connection settings (Notify, Ask, etc). Doesn't work.

I don't know what else to do at this point. And while having to do the airplane mode trick is a small little task to perform, I shouldn't have to do this. When I leave a wifi connection, the phone should seamlessly swap over and connect to cellular data services. And when I'm out and about I shouldn't be losing data services as frequently as I am. I don't know if its Apple, AT&T, both of them, software or firmware issues, but I'M OVER IT and almost ready to swap phone brands and carriers.

Anyone have any insight or experiencing similar issues? HELP please!