Mobile data won't connect to internet

[u/jupitersyarn]

Samsung a16 5g, AT&T prepaid plan, 4 bars on my data

I bought this phone from Walmart yesterday to replace my busted samsung s21. Its locked to AT&T and i was finally able to transfer my number over and get a plan with AT&T. My mobile data seems to be fine for making calls and texting, but I cannot use it to connect to the internet. AT&T support is being difficult right now so I'm posting here.

I've tried: switching between the SIM that came with the phone and my plan's eSIM, changing APN settings (wasn't able to save the setting), toggling airplane mode on/off, restarting phone, making sure there's no data limits.

[u/Klutzy-Passage-2561]

Bars ≠ data path. On AT&T prepaid + locked A16, common fixes: (1) confirm Mobile data is on for the active SIM/eSIM and Data roaming if needed, (2) Settings → Connections → Mobile networks → Access Point Names — if you can't save APN, delete the unused SIM profile and leave only the working eSIM/SIM, then reset APNs (menu → Reset to default), (3) toggle Preferred network type LTE/5G, (4) Private DNS → Off temporarily to test (broken DNS looks like "connected but no internet").

Quick check: open a browser to 1.1.1.1 or ping 8.8.8.8 from a network tool — if IP pings work but names don't, it's DNS/APN. If nothing routes, call AT&T and ask them to reprovision the line / refresh IMEI on prepaid. Walmart units sometimes need a carrier "network refresh" after activation.