My data turns on but won’t work.

Whenever I turn on my data my phone says it’s connected to 4G, but when I try to do anything with internet it says to connect to internet or turn on my data. My WiFi is off, my airplane mode is off, it’s on the most recent update, and I’ve tried all the troubleshoots I can find. I restarted my phone, I turned on then off airplane mode, I reset the network settings, I even completely factory reset my phone. AT&T tech support said that my data was perfectly fine on their side, and even reset my plan and it still won’t work. I don’t know what the problem could be. I’ve never had problems with it before.