cannot activate cellular data network

Hi, I came back to the States from my home country and tried to use the same SIM card that I used to use on iPhone 11.

Here's a thing,

Everything works fine, I can make a call, text, and pretty much all things except my data.

( I double checked with my ATT account to make sure I paid all my bills and got my data left for this month)

Following some suggestion for the problem, I turned on/off my cellular data like hundred times, restarted my phone, tried to get the repair iOS system thing connected, erased all the content and backed up my phone

Yet, I can't connect to my cellular data. Please let me know what to do in order to fix this problem

Thank you!