The units are Too Far apart.
Too far, you may also see a rotating/cycling zero with red arrows on your Coverage Unit. Your Coverage Unit is “Too Far” from your Network Unit. Try moving the units slightly (5-10 feet) closer together, starting with the Coverage Unit.
Intermittent “Too Far” message? Frequent or intermittent issues can be related to heavy WiFi saturation in your home/office. Make sure that each unit is as far as possible from any access points or other WiFi enabled devices.