Windows 10 "Update Over LAN" Option Not Working

I am having issues with the "Get updates from and send updates to PCs on my local network" option on Win10.

A bit of a background on my setup --

I have 2 desktop PCs and 2 laptops (all Win10 x64 Pro) on the same home network and homegroup. By default, I use the following options on all four PCs:

1. Defer Updates - ON


2. Get updates from and send updates to - PCs on my local network

In order to conserve bandwidth and time (and save me from troubleshooting in case an update messes up something), I first update one desktop PC:

1. Turn off Defer Updates option


2. Let it update completely


3. Restart and check if the update doesn't cause bluescreen or other errors

After confirming that everything's OK on the first PC, I turn off the "Defer updates" option on the other 3 PCs and initiate the check for updates.

HOWEVER, upon monitoring the update progress of the three, it seems that each have been downloading updates from MS servers, instead of using that of the initial desktop PC. Monitoring ethernet/wifi use on task manager for the three PCs confirms this (slow speed, total bandwidth used is equal to ISP subscription).

I do understand that driver differences might be taken into account, but currently, I have only one item on the update list -- "Upgrade to Windows 10 Pro, version 1511, 10586". So no drivers right now.

Is there any fix or way to have Windows 10 use updates already downloaded on other PCs on the local network? The current update which is 4GB+ in size, if downloaded four times is quite excessive and inefficient IMHO.

Thanks in advance for any replies/ insights/ suggestions/ solutions :) Should anyone need further details, please let me know.

Add: Come to think of it, Windows Defender definitions seem to be downloaded separately too (not from local PCs that already have the definition) as I've monitored these past 2 months.