You do not need to unplug any cables from behind the NAC.Sorry for English.
But if you have BTA and what to use internet from mobile phone (bluetooth, usb cable, wifi hot spot) it is possible but must remove cable from NAC that connect NAC and BTA.
I tested on NAC Wave 2, only when unplug cable you have option to select other internet source (green usb fakra cable on back of NAC).
I learned that when my BTA module broke. I don't find any other method to disable BTA internet when cable is plugged in.
When operators disable 2G or 3G this can be one solution.
On NAC Wave 4, you just need to go into the settings in the NAC and the phone. I would be surprised if it it was different on NAC Wave 2.