Win10 Home installed on 2 desktops and a laptop. They are networked together via ethernet cable. They belong to the same homegroup, and all "sharing" is working fine. .

My internet connection at home is a metered connection via Jetpack. My home network (ethernet) is based on a dd-wrt router in gateway mode. The gateway router is then one client on my Jetpack internet router.

On all 3 machines, I stopped and disabled the Windows Update service to avoid losing all my bandwidth to auto updates.

Yesterday, I took my laptop to work (unlimited data). I enabled and started the Update sevice. I checked for updates and let it download and install until the WU utility said my laptop was up to date.

Then I brought the laptop home, turned off the jetpack to disable internet, cabled the laptop to the ethernet network, verified network and homegroup comms, verified that all three machines we set up to receive updates "from more than one place" with "local network" option selected, then I enabled and started Windows Update service on all 3 machines, and went to bed.

My hope was that the 2 desktops would update from the laptop.

Nothing happened. No P2P updates occurred.

I did some more reading and found the following paragraph:

When Windows downloads an update or app, it will look for other PCs on your local network that have already downloaded the update or app using Delivery Optimization. Windows then downloads parts of the file from those PCs and parts of the file from Microsoft. Windows doesn’t download the entire file from one place. Instead, the download is broken down into smaller parts. Windows uses the fastest, most reliable download source for each part of the file.

So it sounds like i need to cable the 3 machines together and enable and start WU service, then turn on the internet and "Check for Updates" on all 3 machines, and then hope that windows will recognize the update files available on the laptop and do some P2P update sharing rather than downloading full update files for each desktop.

In other words, it's really out of my hands? Is that right?

Is there a command or trick for forcing a desktop to try to find updates from an ethernet connected laptop that belongs to the network and is even in the same homegroup?

Must the networked machines be connected to the internet for the update sharing process to take place?