We blew it--we missed the diagnosis. The instability issue in the Tuesday post persisted, intermittently, for the next two days. The problem turned out to be a faulty router power supply that was dropping power output level intermittently, which caused very confusing routing and authentication issues that appeared variously to be configuration problems, radio interference, or ethernet connectivity issues. We eventually solved the problem with a replacement of the power supply late Thursday afternoon.
Our New Years Resolution and promise to all: We are redesigning for all-DC power distribution and monitoring for all power parameters at major nodes, with automated alarm thresholds., to be instituted completely in 2014.