The Geochron Digital is incompatible with some legacy Apple AirPort routers. These routers were discontinued. Geochron Digitals work fine on ethernet, but the WIFI incompatibility arises from the use of WMM (Wifi Multi Media), which is turned off by default in most routers. Apple uses WMM, and it cannot be turned off.
Geochron has field tested Apple Airport Extreme and Express routers, and they do not work on WIFI with Geochron Digitals.