So, I have the same issue. The problems started about 10 days ago, when, firstly, the wifi would drop out and then the Smarthub would reset itself. This progressed to a complete inability to log onto the internet via wifi; my iMac is connected via ethernet cable. The internet connection is in and out all the time. Did everything you could to rectify the issue - as explained by a couple of people.
Contacted customer support, who said the line itself was OK. It 'puzzled' the customer services guy (no surprise), even after checking with his mentor (yes, 'mentor'). He ordered me a new Smarthub - arrives tomorrow.
I have had nothing but trouble from the Smarthub, so my plan is to see how the new Smarthub plays, but then use it only as a router, opting for a better wifi network (Orbi etc, etc).
