Windows updates

Win 10Pro, 1809, 64-bit.

Had it check for updates today and it offered Windows Defender definitions 1.283.2822.0. I had it check for updates a second time because that WD update seemed to have gone much too quickly. WU said "fully up-to-date".

But, when I looked at the update history it says definitions 1.283.2822.0 failed on 1/12/‎2019 with error code 0x80240017. and it also said 1.283.2825.0 was installed at 3:00 AM this morning. 

So why did WU offer 2822 now if 2825 was already installed? How is PC waking up in middle of night to look for updates when my WiFi router turns itself off automatically from 11:00 PM until 7:00 AM? And PC isn't connected via ethernet...???