Nokia X6 (2019) - AT&T 4G Won't Connect and Texts Dropped

[noname2020x]

Title is supposed to say 2018! Ooops!

I got a new phone! -- I ordered the new Nokia X6 from ebay: This exact model.

I love it. it's everything I want in a phone... but it won't connect to 4G and I keep missing people's texts.

I've tried resetting the wirless, making my own APN (using ATT suggested settings), and restarting it to no avail. It it just an 'H' (with the up and down arrows) connection. I am in Charlotte, North Carolina which has great coverage.

Unless this site is wrong, it has plents of bands to use: http://www.china-prices.com/phone/bands/12750/nokia-x6

Something I assume is important to note: Upon restarting the phone says "Your device has loaded a different operating system. ID:[bunch of numbers and letters]"

Oh, also, what is SIP and should I have it set to "for all calls"?

What's the deal? What can I do?

Thanks!