RHEL7.6: NFSv3 client hangs after 5 minute idle timer drops the TCP connection and a subsequent TCP 3-way handhake fails due to duplicate SYN or unexpected RST from the NFS client

Issue

• On an NFSv3 client, a NFS share that was previously active goes idle for 5 minutes and the NFS client initiates a close of the TCP connection. After some time, a process accesses the NFS share and the NFS client attempts a 3-way TCP handshake to the NFS server. During the 3-way handshake, the NFS client issues either a duplicate SYN packet for the first part of the 3-way handshake, or issues an RST to the response to the second part (SYN,ACK from NFS server). As a result, the NFS client is unable to complete the TCP 3-way handshake, and the NFS share hangs.