This counter tracks the number of received packets that were discarded because they failed validation under strict security checks or contained encrypted data that could not be decrypted. When secyIfvalidateFrames is set to 'strict' mode or when encrypted packets are encountered, this counter increments for each rejected packet. Operators use this metric to monitor how many inbound frames are rejected due to MACsec validation failures, indicating either misconfigured security policies or potential network attacks.