Zombie sockets from dissociated WiFi client due to inactivity

The OpenWRT device is running as an WiFi Access Point, without nat, which means that I can check the exact source ip at upstream main router which runs OpenBSD .

Today I found out at the upstream main router that several active TCP connections from a deauthorized/dissociated WiFi client. I am wondering if it is possibly due to an OpenWRT bug which leave the sockets unclosed when dissociate a WiFi client.

AFAIK, it is the client's responsibility to close any open sockets. I think that this issue would present for any AP (regardless of the firmware) if a client is disconnected abruptly.

Obviously it depends on the process/services, but often a client will open a socket, perform whatever transaction is required, then close the socket. If it is left open by the client (by design or by circumstance), ideally the server will have a timeout after which it will close the socket, should that be necessary for it to operate normally under other circumstances.

I don't believe that this has anything to do with OpenWrt.