I ran through the 7 upgrade docs. Checked what it suggests. I don't see any problems.
I'm watching zentyal.log, and nothing gets logged when the system stops routing WAN traffic.
If I click a "Change" button for an interface, the orange Save button lights up. Clicking that gets things working again for another 10 minutes. It takes about five minutes.
Syslog gets a LOT of entries.
Is there something I should look for, explicitly?