iPhone 12 dropping signal

I replaced my 6s less than 2 months ago with a 12 Pro Max and have had nothing but issues with it. I can not use the phone for more than 10-15 minutes before it drops the cell signal and has no service. I have to restart the phone to get service back and it never lasts more than 15 or 20 minutes before it happens again. I also have an iPhone 11 for work and an iPad and this does not happen with them - so it's clearly not an issue with my carrier or my tower. (I work from home) It's definitely this phone. I can have all 3 devices going at once and it's always the 12 that drops the signal every time. I've read others have had this issue as well. Any resolutions? I'm to the point where I'm going to put my SIM card back in my 6s which is pretty bad.