I had something similar and the answer was that the system had to be able to access GPS as well. My boat was on the trailer in my metal building / garage and I had full high speed wifi, but the TZT3 was not getting a gps signal. I was trying to synch some waypoints and it would not sync to Timezero, and I believe the menus were grayed out. Once I rolled the trailer outside and picked up GPS, everything worked like normal.