W5500 always send RST in TCP handshake

TCP/IP Chip W5500
1

Dears,
I’ve got a wiz55io module.It work fine with PING.

I write a Modbus TCP server program from Freemodbus.But it can't work.I capture the data to analyze this problem.I found the W5500 always send back RST in TCP handshake.
Then I download a TCP_loopback program from website.It still work fine with PING,but still send back RST in TCP handshake.
I don't know what wrong with it,please give me some advise! Thank you all.

STM32_W5500_Modbus_TCP_V1.zip (376 KB)
handshake error.rar (187 KB)

1279×270 220 KB

2

I’ve already know what’s the problem is.
TCP initialize error.I’m doing with it.