Need to communicate between a VB6 SERVER and a FLUTTER CLIENT over LAN

Currently i'm using Winsock in VB6 and Websock in FLUTTER - but when trying to connect i receive this message:

accept-encoding: gzip
sec-websocket-version: 13
host: 10.100.102.2
sec-websocket-extensions: permessage-deflate; client_max_window_bits
sec-websocket-key: +jQkmsW7I1JZXTYMo+IHuA==
upgrade: websocket

And after that, i cannot send messages between them..
I need the FLUTTER CLINET and the VB6 SERVER to communicate over LAN

* ALSO possible: if you have other ideas how to communicate between them (without middle server)