This read-only MacAddress, held on the ComController, identifies which ComPort a row in the ATM per-queue traffic statistics table belongs to, distinct from the RF-transport stats table keyed by stuStatsMacAddress. An admin uses this to make sure a given queue-level throughput or drop reading is being attributed to the correct subscriber's STU. For example, before escalating a report of dropped cells on a specific queue, support confirms stuAtmStuMacAddr matches the affected customer's STU.