I have two Pi B+, one running Jessie and the other Stretch. They both have 3G USB dongles attached which I use for remote data collection.
Once a day I bring up an internet connection, send 50-100KB worth of data and then take down the internet connection. The unit running Jessie has worked well for the last year or so.
The problem I am having with the unit running Stretch is that when I connect to the internet it seems to download 5-30MB of who knows what … as well as sending the data.
Looking through the syslog I noticed calls to apt-daily.timer and apt-daily.service, so after reading several suggestions these have been stopped by purging unattended-upgrades. I don’t see anything in cron.daily/hourly/weekly.
Is there something else that I need to disable?