No data access on ATT prepaid but my plan has data

[dc2daylight]

Not sure if this has been answered elsewhere (forum search feature kind of weak), but I'm using the PinePhone with default manjaro distro, just loaded the latest updates. My plan is AT&T prepaid, $30/month which includes 5GB of data. Phone and SMS seem to be working but when attempting to use data, for example with Angelfish browser, it keeps redirecting to ATT site saying my plan has no data. That site will actually allow me to log in, it shows I still have 5GB available.

I wonder if it's some simple configuration thing that is different on ATT prepaid? Or is ATT prepaid blocking this specific device from their data network, if so can I spoof some acceptable device?

Should I switch to a different distro?

Thanks for any insights.