TCP connections hang occasionally and retransmissions are not seen in the pcap

Issue

• ss -antpoi shows bytes in the TCP sockets send queue but "retrans:0/1" stays the same over the RTO duration instead of increasing to indicate retransmit.
• Retransmit is never sent, pcap verifies receiver not sending Zero Window.
• nstat TCPSpuriousRtxHostQueues increases at the same time.
• TCP connection will stall for multiple seconds or may get terminated if the other endpoint times out.