Sixfab Raspberry Pi NB-IoT Shield is not connecting to Turkcell operator

I’m working on a very urgent project using the Sixfab Raspberry Pi NB-IoT Shield with Quectel BC95-B20 module
I want to connect it to a “Turkcell NBIoT cellular network”, I am following the instructions in the example for manual network attachment process in pages(123-124-125) of the “Quectel BC95 At commands” document.
But when I send the following At commands to configure the APN:
(AT+CGDCONT=1,“IPV4V6”,“nbiot”) # pdp-type is IPV4 for Turkcell APN connection
I get the following error: (+CME ERROR: 50)
According to the 7.chapter “Error values” in the document this error refers to an (Incorrect parameters)
and when I use the AT+CGDCONT=? command I get the following response:
so as you can see only IP and NONIP pdp types are supported
Would you please help me solving this problem? will a firmware update solve it - if so how can I update the firmware-?
or maybe resetting the module to its factory settings can help?
I searched a lot for a solution but unfortunately I couldn’t find any
Your help is greatly appreciated. Thanks!