Automatic upgrade starts right after resume, before the network is up, and installs nothing #1109

Linux Mint 22.3, mintupdate 7.1.4, laptop on Wi-Fi that is usually asleep or hibernated at midnight.

When the daily time passes while the machine is asleep, mintupdate-automation-upgrade.timer (Persistent=true) starts the service as soon as it wakes up. On this laptop that is 0.1 to 0.2 seconds after resume, while NetworkManager is still disconnected. mintupdate-cli then can't resolve any repository and nothing gets installed. The next attempt is the following day.

The service has After=network-online.target, but that target is reached once at boot and stays active through suspend, so it doesn't hold the service back on resume.

One example from the journal:

Oct 22 13:51:22.693 systemd-sleep: System returned from sleep operation 'hibernate'.
Oct 22 13:51:22.829 systemd: Starting mintupdate-automation-upgrade.service - Update Manager automatic upgrades...
Oct 22 13:51:24.282 NetworkManager: manager: NetworkManager state is now DISCONNECTED
Oct 22 13:51:28.059 NetworkManager: manager: NetworkManager state is now CONNECTED_GLOBAL
Oct 22 13:51:35.931 systemd: Finished mintupdate-automation-upgrade.service - Update Manager automatic upgrades.

and the matching part of /var/log/mintupdate.log:

W:Failed to fetch https://mirror.vnet.sk/ubuntu/dists/noble/InRelease  Could not resolve 'mirror.vnet.sk'
[same for every other repository]
Error: mint-refresh-cache could not update the cache.

Between Oct 5 and Oct 29 there were 25 automatic runs. 10 failed like this, and 9 of those 10 started within 0.2 s of a resume from suspend or hibernate. Four days in a row (Oct 22 to 25) got no updates.

The service still exits with status 0 after these runs, so systemctl reports them as successful and the only trace is in mintupdate.log.