I have Windows Defender, just what's built into Windows 10. Since I have had to shut the internet off in order to not have this computer take over the internet bandwidth, it starts downloading whatever new updates there are when I turn it back on, then it starts back all over again on the feature update. I already had reserved an entire day to not use the internet for any other purpose but downloading this feature update a few weeks ago. It got to 100% downloaded and said it needed to restart to complete the installation. When I restarted, nothing happened, no installation, no messages.
Now, it seems to keep repeating this process. The cumulative Windows 10 update downloaded and installed yesterday. It said it needed a restart to complete the installation for the cumulative update and after restarting, that was successfully installed, but the feature update started the download all over again. Once again, taking all the bandwidth from the everything else. Looking at the update history, I see it says failed to install Feature Update 1709 a bunch of times.
I did already install the feature update 1709 on my laptop, so I know how it was supposed to work. This other computer is my desktop, which, except for this internet update problem, is much faster than my laptop, so I don't like having to keep this constant download in limbo. I would have preferred Microsoft not have feature updates mandatory, but since there doesn't seem to be any way to permanently decline the update, I would rather get it over with and not be bothered about this continually. Unfortunately, it seems even if I leave this computer on all day, it will just go through the same loop of starting the download all over again and not accomplishing anything, at least with the feature update.