problem to send data by TCP with iolib

I try to use the lib iolibrary with a w5100 chip on a microchip pic32
I succeed to communicate with the chip and I resolve to connect to a tcp server on my computer (in python)

But I have a problem. I try to send a byte every 200ms. It seems to work on the begining and after I receive a lot of random data and I have a brutal disconnection.
On my python script I have this result

Python 3.8.1 (tags/v3.8.1:1b293b6, Dec 18 2019, 22:39:24) on Windows (32 bits).
This is the Pyzo interpreter with integrated event loop for ASYNCIO.
Type ‘help’ for help, type ‘?’ for a list of magic commands.
Running script: “C:\Users\antho\OneDrive\Bureau\”
Connection address: (‘’, 3000)
received data: b’U’
received data: b’U’
received data: b’U’
received data: b’U’
received data: b’R\x86S\x00Q\x84N\xd6<\\x08\x80\x11*:\x9f\x94A\x0c;\xfa\x11\xc5Aj\x11R\xe2\x8a\x99\xea\xa8a\x04\xf3*\x0cR\xb0\x8b\xa5\x1e\x0c!\x80i\x07P\xe4%’
received data: b’\x0c\x00A\x8f\x00f\x80\xd2\x88\x8a* \x01\x03 \xe4"e(\xb0\x90\x0c\rQ\xd0\x08\x0e,Q<f\x18\x12d\x98\xe0\x04\xa9\xca\xcbaH@\x02\xd94\x06\x86\xa8m’
received data: b’\xa3#[3\xc8\x8a1PH&\x04Y\x02\xa6\t\xd8\xf3 \x14^4\xe2\x18\xf4D\x06c\x16Q\xa5fH\x11n\xcc\xe1H\xd7\xb8\x15\x05\xa0\x98)\xd2\@dS\x13’
received data: b’U\xdc\x02\xa2\x97\x9c\x00\x91X\n\xaas\x80\xa0\x80@-Y\x1c\xe2\xa8\x08\x86TQ\xa1\x191\xd5\xc5\x90\x86 \x90L\x11\xb0\xad\x08\xba\x81\x0f\x02\xb0Z9\x04\x93\xa3\x17’
received data: b’\x998$d,\x0e\x016\xd0\xb2\x9c\x88D\x96b#\x0f0\xa8\xd1\x02\x1c\x8a\xed\xce\x1ad\xd0\xc4&\x01\x10\x02?\xb2?\x05q@ \x88X\x17Q\x18\x18\x91\x04\x10\x80’

On my micrhip pic 32 I would like to send ‘U’ → 0x55

I have this code on my Microchip

wiz_NetInfo gWIZNETINFO = { .mac = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED},
.ip = {192,168,0,15},
.sn = {255, 255, 255, 0},
.gw = {192, 168, 0, 1},
.dns = {168, 126, 63, 1},
result = socket(0, Sn_MR_TCP, 1000,0);
uint8_t adr_ip[4] = {192,168,0,16};
result = connect(0,adr_ip,1000);
uint8_t test_buffer = 0x55;
result = send(0, &testBuffer ,1);

Sorry for my bad english…

Please check whether it is correct to actually send random data from W5100 through wireshark.
I think there may be a problem with your python script.
Or test it with other tcp tools instead of python.