One day while copying photos and videos from iPhone to Windows PC, I got a “Device is unreachable” error. On the next attempt to copy, this error occurred immediately and the copy was not performed at all.
Solved this problem in the following way, opened:
Settings – Photos – TRANSFER TO MAC OR PC – Keep Originals/Automatically
and switched to “Keep Originals”, and then back to “Automatic”, after that I connected the iPhone to the computer and the copying was completed successfully.
Of course, you can leave “Keep Originals”, then the video will not be in .mov format, and you can also switch it in the menu
Settings – Camera – Formats – Most Compatible instead of High Efficiency.
However, it’s still better to leave “High Efficiency” and Auto mode, so the video on the iPhone will take up less memory, and when copied to the PC, it will be converted to a compatible format.
To reduce the error, close open applications on the iPhone and do not use it during copying.