[Aerofly]

The car has its own data sim which connects the infotainment system to the Kia Network, so it could be that the network coverage in your area is weak for the network used. I believe Kia use the Vodaphone network. It might be wise to try moving your car to somewhere where the signal is a bit stronger (check using a network check website) and trying again.

 

[Aerofly]

I’m not sure if the native sat-nav should still work, as I use Carplay. When you look at the top right corner of the Infotainment screen there should be a signal strength indicator which a lot of people believed showed the mobile phone signal, but is in fact the network signal strength of the Kia SIM card. Does it show on yours?.
Someone had a similar problem but I can’t find the thread now, however the problem was solved for them by contacting Kia support who reset the SIM remotely. Kia Customer Support number is : 0333 202 2990. Might be worth a call if all else fails.

 

[Aerofly]

I believe the signal strength indicator in CarPlay is the actual phone network strength signal, not the car’s SIM signal, so if you don’t see it on the Home screen it’s looking like the Kia SIM is not connecting to the network.
I think you need to speak to customer services. They can either talk you through removing Kia Connect and re-adding it, or as I said previously re-setting the SIM.