That does sound unusual. When you say the 'relay click several times per second' is the plug itself turning on and of that quickly? You can confirm by connecting a lightbulb to the plug. The plugs will flash when loosing signal with your router, thorough they should automatically re-connect. Can you confirm the plugs are located in in area with strong wi-fi signal and try moving them closer to your router? It sounds as if the plugs themselves are not properly paired to your Wi-Fi.

  @Otrip  Yes that quickly, with no load attached, nothing plugged in. Has nothing to do with the wifi source which is within 8 feet. It starts flashing instantly as I plug the smart plug into any outlet!

  @DDatt 

The plug itself flashing quickly means it is in pairing mode.

Too strong if a wifi signal can ovetload the plug.

But if the relay in the outlet itself is turning on/off confirmed by plugging a lightbulb into the Kass then that is a big problem that the Kasa engineers need to investigate. 

  @Otrip No. It flashes several times per second (Like a machine gun), whether a light is plugged in or not, a lot faster than the pairing mode. There are 2 identical KASA smart plugs closer to the router than this one without any issues. It's as if the PCB has failed solder connection.