@ImtiazAli  thanks for the link. I did go thru that previous to posting, and all signs point to this particular unit having faulty ports. My current set up works in every way except this problem unit does not detect when an Ethernet cable is connected. My other two units can be swapped or rearranged on every Ethernet cable in using and the units and the switch work as intended. The problem unit will not detect when it is directly connect to the switch or one of the other units. Unless there is something I'm overlooking, I am chalking this up to a defect in this unit. 

  @Maksidaa 

That looks like defective unit, but for the certainty I would recommend the following test: have that unit connected wirelessly to Deco mesh. Position it in such a way that it reports Excellent or Fair signal. Connect device such as PC or laptop with Ethernet cable to that Deco unit.

If wired to that Deco unit PC/laptop can't get IP address and Internet access, that strongly points at issue with Deco unit Ethernet ports. Try both Ethernet ports to be sure both are not working.