This counter increments for each byte of IPv6 TCP traffic that arrives out-of-sync (disordered or duplicate), indicating packets that do not follow the expected sequence. Out-of-sync traffic often results from network loss, reordering, or packet retransmission, and high counts can degrade application performance. A network analyst would monitor this metric to detect TCP retransmission issues, path instability, or congestion affecting IPv6 traffic flows.