anyone have a fix for iphone 15 pro max issues

When I first traded my 13 pro max in for a 15 pro max it was great. Then the first update came. The 15 started to have problems, blue tooth always dropping in my car. Never got more than 1 bar service. Then the next update came along with new issues. Wifi constantly needing to be turned off and on to work, poor battery life along with all the other previous issues still there. IOS 18 comes along and now the phone will not play a video longer than 5 seconds without buffering like it’s internet from 1999. Fb and insta reels, you tube, tiktok, you name it, it buffers! iOS 18.1.1 comes out and in hopes to fix everything I install it. Now FaceTime calls say “poor network connection” with FULL BARS AND WIFI ON” turn wifi off and same thing. Videos STILL buffering after a few seconds of play back. Really regretting getting rid of my 13 pro max for this phone. Past warranty, tried resetting everything, tried wiping fresh, after seeing hundreds of similar posts it looks like the 15 is a terrible phone as I’m definitely not the only one with one or more of these issues. If anyone has a fix I’d love to hear it