TCP out of state drop observed before the timeout configured in firewall

[praveshnayal]

Hello all,

We have encountered TCP out of state drops stating First Packet isn't SYN just after 10 mins of the connection initiation from the source. (After inactivity)

The timeout configured in the service port is default 3600 seconds so as per my understanding the connection entry should be there on the firewalls for 1 hour but in this case once the user returns to the application after 10 minutes the user gets disconnected and we can see out of state drop logs as mentioned above.

What could be the possible reasons for this behaviour? 

Thanks for any suggestions in advance.