No, Your iPhone Is Not ‘Mysteriously Rebooting’: Here’s What’s Happening

404 Media also goes into more detail of exactly what’s happening and, crucially, when. According to Chris Wade, founder and CTO of the cybersecurity startup Corellium, the reboot happens after four days.

Well, that’s information which will be useful to the police in Detroit, who can simply ensure they access each iPhone before the four days’ limited expires.

Of course, as the report goes on, it means that the real target of this update, criminals who have stolen your iPhone, will also now know to check in with the phone every few days. As cryptographer Matthew Green pointed out to 404 Media, “This feature means that if your phone gets stolen, the thieves can’t nurse it along for months until they develop the tech to crack it. I would bet that rebooting after a reasonable inactivity period probably doesn’t inconvenience anyone, but does make your phone a lot more secure. So, it seems like a pretty good idea.”

The original issue was making police in Detroit think that a series of iPhones were sneakily communicating with each other, as we’ll discuss below, but a new report talks about a “hidden feature,” as Charles Martin at Apple Insider describes it.

This feature is called inactivity reboot and it means that if the iPhone hasn’t been unlocked for a certain period of time, it will automatically reboot. Rebooting puts the iPhone in a state where a physical password is required to unlock it, “and is similar to a feature found on Macs. The Mac version, known as ‘hibernation mode,’ saves the state of the device to disk when put to sleep, in case the power fails or the battery runs out before the user can return to the machine,” as the report describes it.

You can do it on GrapheneOS if you have a Pixel phone

I sometimes catch my Motorola doing that at night, sometimes it even updates.

My pixel 6 doesn't "reboot" but every few hrs the lock screen changes to needing the pin code

Graphene OS has this after 18 hours I think and Calyx I think has it after 48.

I had an android phone that always rebooted (due to bugs) and it’s something that you don’t really want unless it’s vital to hide stuff from forensic investigators

When the phone is in “after reboot” status, absolutely nothing works, no email, no instant messaging and so on