Hi Kevi, I have had similar issues, with a separate wired modem and wireless router, when power goes/ storms / telstra issues etc.
As crazy as it sounds, the ol' "switch it off then back on again" sometimes does the trick for me.
I assume you have a wireless router? Do your devices still find and connect to your home network? And if so, can you get to other internet sites okay without having to go 3G??
