On my G12 in the UK, (Order SP-DA5357), I cannot get the 4G mobile connection working, I have tried so far, 2 different SIM cards, Three and Vodafone, both of which have an excellent signal in my phone, but in the G12 they are both recognised as being plugged in and the network is recognised, but both say 'disconnected', and a working connection is not possible.
I've tried the antenna supplied with the G12 and bought another on Amazon in case the original was faulty, but the result is the same, so definitely nothing wrong with the antenna or either of the SIM cards.
I've also confirmed the APN details for both SIM cards are correct, and factory reset the head unit several times, I've tried and checked everything I can think of so any suggestions would be most welcome.
Also on the same G12 with the supplied external microphone call quality through CarPlay is horrendous, the other caller cannot hear me, it's unusable, but on a call through Bluetooth without CarPlay the call quality is great, it just will not read my phone contacts, not much good though when I mostly use CarPlay.
I've seen another post elsewhere about de-soldering and removing the built in mic, I'm ok with a soldering iron but would that cure the problem ?