What I have found is that the system does not always restablish connectivity after a power outage. I never could figure out if this was a modem issue, router or panel. What I did find is that the system did stay armed and would work through cellular. So protection was never lost. That is good. But the web portal, rules, iphone apps, and such will not work in that situation. You just have a "dumb", but functional, system.
To solve the problem I plugged the modem, router and touch panel into a UPS. No more problems with connectivity. So for under $50 problem solved.