He complained about the same thing, in this case on laptops that were completely shutdown the night before. In the end we tracked it down to the Lenovo Vantage service.

I assume it was powering on the laptop to check for updates but I could find no log or record of it doing so. But, once we removed that software the issue went away completely.

Anecdotal I know and I even told him it could be something else, that removing the software may have changed something related but not from Lenovo, etc. But in the end, a few weeks later that is, he confirmed that since we did that, they did not have the problem again.

Mine used to do it at midnight and wake up my desktop till I gave it a static address