How to operate w5500 client to send RST ACK message

Hello everyone, the current application is as follows: the w5500 client communicates with the server. If the w5500 client is powered off and powered on again at this time, and the macraw function is not used at this time, the w5500 client can immediately connect to the server through the same local port. If any socket runs macraw mode, other sockets cannot immediately reconnect to the server with the same local port.
After packet capture analysis, it is found that when the macraw mode is not run and the power is lost and reconnected, the w5500 will send the message of RST ack to the opposite end, and the server can reconnect immediately after receiving it. When the macraw function is enabled, the w5500 does not send RST ACK message, resulting in the inability to reconnect the server immediately.

  1. W5500 local port must be fixed
  2. After power on, the macraw mode must run immediately because there is a pn-dcp protocol that needs to be parsed
  3. The server is a Siemens PLC device. Its keep alive is fixed at 30s and cannot be modified. If the server is powered off and reconnected, it will take too long to wait for 30s.
    Current demand:
    Can you provide relevant information on how to operate w5500 to send RST ACK message.

W5500 TCP client IP:
PLC server IP:

Power failure reconnection without running macraw mode:

Power off reconnection in macraw mode:

WIZnet FAE colleagues, please help answer, thank you