Correct, Bill. This is on a home network behind a Linksys router. All of my
test systems at work (I run the networks there.) are working just fine with
WSUS and WD.
I have resolved the issue, however. Although the use of the MSKB solution
referenced many times here did not work, and my initial use of the Installer
Cleanup Utility did not work, I tried removing ONLY the Windows Defender
update signatures on that machine using the cleanup utility this afternoon.
(Previously, I had tried removing WD and the signatures, but not the
signatures alone.) I then clicked on the autoupdate shield, and the
installation reported failure! But a few seconds later, as I was gritting my
teeth and getting ready to uninstall WD from the problem computer entirely, a
pop-up in the system tray announced that Windows Defender was completely
up-to-date! I checked, and, sure enough, there sat 1.13.1276.16.
I want to thank you for your assiduous attention to detail in this, and
other, matters. I had communicated with you about this machine briefly in a
couple of other threads but had simply been overwhelmed with too much other
stuff to be able to follow up in a proper manner. Your efforts here are much
appreciated.