esaProbeHistoryR2PSyncErrs is a 64-bit performance counter counting timestamp synchronization errors between the probe and reflector clocks encountered while measuring the reflector-to-probe (R2P) leg, for a completed interval that has already closed and been archived into the rolling history log. Because one-way delay and jitter depend on the probe and reflector clocks agreeing, a technician checks this counter first; if it is non-zero, the one-way numbers in that same bin cannot be trusted. For example, an archived bin with a burst of sync errors right when a temperature alarm fired lets a technician tie an oscillator/clock issue to a specific past event instead of a real network fault.