In case some of your machines need to be updated automatically, you can disable the automatic upgrades in the following file :
Note: the naming of auto-upgrade script located in /etc/apt/apt.conf.d/ could be subjected to variations, usually the number indicating the read priority is the variable part and the file name will contain the “auto-upgrades” suffix.
Then, change all the values matching the pattern APT::Periodic::* to “0” :
APT::Periodic::Update-Package-Lists "0"; APT::Periodic::Unattended-Upgrade "0";
The changes will take effect immediatly.