I have not had this problem myself, but here is some information from an AI search related to the problem. Please post back if this is helpful.
To force CarPlay to use cellular data,
disable "Auto-Join" for your car's Wi-Fi network in your iPhone's Wi-Fi settings, or configure the car's network with a static IP address (by filling in the IP address and subnet mask while leaving the router blank) in the
Configure IPsettings. This prevents your phone from using the car's network for its internet connection.
Method 1: Disable Auto-Join
This is the simplest method for preventing your iPhone from automatically using the car's Wi-Fi for internet.
- Connect to CarPlay as usual.
- On your iPhone, go to Settings > Wi-Fi.
- Tap the information icon (the i in a circle) next to your car's Wi-Fi network name.
- Turn off the Auto-Join setting.
- Do not tap "Forget This Network"; just disable auto-join.
This video demonstrates how to disable Wi-Fi auto-join for a specific network:
View attachment 3992012View attachment 3992011YouTube• Cars Unlocked
59s
Method 2: Configure a Static IP Address
This method forces your iPhone to always use cellular data when connected to the car's Wi-Fi, effectively bypassing the Wi-Fi connection for data services.
- Connect to CarPlay wirelessly.
- On your iPhone, go to Settings > Wi-Fi.
- Tap the information icon (the i in a circle) next to your car's Wi-Fi network name.
- Tap Configure IP and change it from "Automatic" to Manual.
- Note the IP Address and Subnet Mask shown on the screen before making the change.
- Enter these same IP address and subnet mask values into the corresponding fields.
- Leave the Router field blank.
- Save the changes.
This workaround helps the iPhone realize that the car's Wi-Fi cannot provide a valid internet connection and will then fall back to using cellular data for CarPlay services.