Documentation for AT+QCFG="dftpdn"

Can someone tell me where I can find the documentation for the command mentioned in the title. AT+QCFG=“dftpdn”
Some of the entries can be found in the AT command manual but others, like this one is not described in there.
I can see it when doing the AT+QCFG=?
+QCFG: “dftpdn”,<ip_version>,<apn_name>,<auth_type>,,

thanks for contacting us, could you please tell us the module type and firmware version? thanks

AT+CGMM returns EG915U
AT+CGMR returns EG915UEUABR02A05M08
AT+QGMR returns EG915UEUABR02A05M08_01.001.01.001