Well, you are implying that this is an Apple problem that affects millions of devices. That is clearly not true, or you would see thousands of reports here and more in the tech trade press. So Apple did not “mess up” something that affects maybe a few dozen devices (or fewer). This is a problem with your iPhone or your cars, or both. As it affects more than one car my bet is on your iPhone.
There are a couple of possibilities. The most obvious one is that the phone is paired with both cars. If both cars are powered on the phone won’t know which car to connect to, and may choose the wrong one. If restarting the phone fixes it that is most likely the explanation. If you start one car, connect, then move away before starting the other car this would be another test.
Less likely, but still possible is based on the fact that Bluetooth is a frequency-hopping technology. When you pair devices they exchange random “seeds” that each uses to extract the Pseudo-random frequency change pattern so they stay in sync. Ideally each pair of devices will have different shift patterns, so there will rarely be a collision. But sometimes two patterns chosen randomly will overlap. The solution to this (if it is the problem) is to unpair the devices at both ends, then re-pair them so they generate a new random number seed.
Even less likely is VPN interference. If you have VPN on your iPhone delete the profile (not just the app).
And finally, least likely, Reset Network Settings:
- Open Settings
- Tap General
- Tap Transfer or Reset Phone
- Tap Reset
- Tap Reset Network Settings
- This will erase all Wi-Fi passwords, but will not result in any other data loss.
