why webrtc connected echo not reply?

[xiangxud]

I use the client-improbable and server programs to test, but when I use webrtc connect, the Web UI message does not echo, and the webrtc peer has been created and connected. Using grpc-web connection can work normally. I want to transfer large files for this package, such as https://github.com/duysmile/grpc-upload-file , how to add and modify?, I found a pilot project github.com/viarobotics/gotutils