This read-only counter tracks the number of cells lost in the egress direction specifically due to AAL-1 header errors or missing cells in the expected sequence. An administrator correlates this counter with cesHdrErrors to distinguish cell loss caused by header corruption from other causes like buffer underflow (cesBufUnderflows). A rising cesLostCells count paired with rising cesHdrErrors points toward a transport-quality problem corrupting cell headers rather than a bandwidth or timing mismatch.