Websocket over TCP implementation error

[Bence Stocker]

Hi,

i made a webscoket server over TCP on STM32F429VI with lwip stack. I would like to use on local network. I used this nectonn examples for TCP communication. The connection and the websocket handshake works fine, the client can send a message to my server. But if my server send a response to the client, the connection will be always closed, because there is an invalid opcode (0). But i think i send valid response, my serever send back "hello", which websocket bytes are in hex: 0x81, 0x05, 0x68, 0x65, 0x6c, 0x6c, 0x6f. Client error log writes OP code is 0. Before 0x81 is a '0', but it should be the urgent pointer of TCP header.

I made a Wireshark printscreen.

Does anybody have any idee, what is the fault?

Thanks!