Here's a quick test I ran this morning for a colleague who need to check if the feature works upon computer reboot (which for the agent is the same as a service stop / start event pair).

So here's the test I conduct:

• Picked up the 4 biggest packages from my PMS update directories
• Created a single package with 900+ MiB from 4 files
• Created a SWD Task and assigned it to my test machine
• Update the client config on the test machine
• Disable the NIC after the download started
• Enabled the NIC and forced the download restart (couldn't wait 4 minutes ;)
• Stopped the Altiris Agent
• Started the Altiris Agent
• Repeated the above 2 steps

And the results are visible here: