I have tried many suggestions, and none of them work. I don't want my Ubuntu system to touch the network in any way shape or form to check for updates until I explicitly run an update check.
I've set the check to "Never" in the GUI app with the repos. I've disabled every systemd timer that says something about update. Still I get update-notifier notifications popping up from time to time.
What on earth do I have to do to stamp out this scourge on Ubuntu 19.04?
Note that I don't want to just disable the update-notifier popup; I want to disable all network traffic doing the update check.
More details on what I have already done:
systemctl disable apt-daily-upgrade.timer apt-daily.timer
Run Software & Updates, go to Updates tab set "Automatically check for updates" to "Never".