Default: the built-in car hotspot
Open Settings → Connection → Connection setup → Built-in car hotspot. Turn on the actual car hotspot, preferably 5 GHz when available, and save its exact name and password. Keep iPhone Bluetooth/Wi-Fi on, pair with the car, tap Connect phone and accept CarPlay prompts.
Compatible firmware passes the credentials through Bluetooth. If automatic joining fails, join the car hotspot manually and record whether CarPlay starts. An iPhone personal hotspot is not a substitute for this mode.
Wi-Fi Direct depends on firmware
Android 7.1+ can try this mode when the required firmware APIs exist. Android 7.1–9 uses generated group credentials without verifying the requested frequency; Android 10+ retains actual-frequency checks.
Auto guarantees neither a band nor smooth playback. Joining 5 GHz Wi-Fi does not establish 5 GHz group creation. Legacy channel pinning and cleanup have firmware limits; compare the car hotspot if unstable, without changing country codes or drivers.
Existing Wi-Fi / Same LAN
First use system settings to join both devices to the same router or portable Wi-Fi. Save the network name/password, keep Bluetooth enabled and disable client isolation so the devices can discover one another.
DiPlay neither joins the network nor changes the default route for you. Core CarPlay needs no ADB; optional hotspot-start features have separate already-authorized local ADB requirements.
USB and diagnostic evidence
Use a USB data port and data-capable cable, then Connect with USB. Approve USB access, Trust/CarPlay and local VPN permission if asked. That VPN carries USB networking, not an internet VPN service. Charge-only hardware cannot work.
Check picture, touch, audio, Siri and calls. Reproduce remaining failures on 0.2.19 and save a report. Android 7.1–9 requests storage access; Android 10+ normally saves to Downloads/DiPlay. Follow fallback paths or View report/Share; no automatic upload occurs.