I believe the culprit on this one was water... which appears to have entered the connector from inside the Cat6 cable. Connection that failed was located in a very dry utility box at base of tower. It attached cable from the node to the PoE injector.
Cable was not goo-flooded nor rated for direct burry; it was our standard, blue, shielded Cat6, with a plastic separater (cross-section cross) running through the center of the cable, and a cellophane wrap inside the foil shield.
I found the wires inside the cellophane to be moist. Cable appears to have acted as a conduit for moisture, ducting water to the connector. We've seen this before with Ubiquiti's Tough Cable.
Photos of the RJ45 plug and the PoE socket are attached. The photo doesn't, show it well, but I can see the blue oxidized copper in the PoE socket.
Bill WA8APB