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I have two devices, a modbus client (10.32.0.131) and a modbus server (10.32.43.32). I have captured the conversation between them at the client end and at the server end. What I see is on the client end capture everything is normal without TCP retransmissions, however on the server side end I see spurious retransmissions. Checking, it seems that in the server-side capture wireshark sees the ack before the tcp query, so it marks the ack as ACked unseen segment and the tcp query as Spurious Detrasmissions. If I remove the option to Analyze tcp sequence numbers, I see the ack before the query as before but this time without tcp spurious retrasmissions. My question is why this can happen and if it is a false false positive spuria retransmission. What is your opinion? Thank you.