Well, my Max just acted strange. I came into my house and it connected to WiFi. But I noticed that it was showing 4 bars for LTE (Verizon). I usually get one or two. So I thought, "Wow, this is great!" I decided to test the speed, so I turned off WiFi. It wouldn't connect to Speedtest at all. None of my online apps would connect, and I kept getting a message to check my network connection. So I put the phone into airplane mode, waited a minute and then took it off airplane mode. Now the LTE signal strength showed two bars. It would connect to WiFi, but still not to LTE. It only connected to LTE after I rebooted my phone.
This sounds like a software glitch to me since this is the first time it's happened, but I can't know for sure. Frankly, Apple should extend the return date for these phones for at least 30 days while they sort out their software. But, of course, they won't so I need to make a decision in the next few days. I've never been this ambivalent about a phone before.
Edit: One other bit of info. While the phone was in LTE limbo, I called my phone from a landline and the call went through.