AT&T network fix

I have received feedback from users that ATT cannot be used. You can try the following steps.

Step 1:
Enter the AT instruction page and execute the command AT+QPRTPARA=3

Step 2:
Confirm the modem version and execute the corresponding instruction
For version R05, execute at+qfopen="../../usr/fota_ip_a/update_report.ur",1
For version R07, execute at+qfopen="../../data/fota_ip_a/update_report.ur",1
For EP06, execute at+qfopen="../../data/fota_ip_a/update_report.ur",1

Step 3:
Execute AT command AT+CGDCONT=1,"IP","broadband"
Then, In modem manual Settings, modify your apn configuration to use broadband and click Apply

Step 4:
Restart your router