UE4: Client receive only an one message after connection and then receive always empty messages

I trying to work with websocket from unreal. And i dont understand what is going wrong when i try to exchange messages.

I use it with this UE4Websocket samples https://github.com/feixuwu/UEWebsocket .

I tried a simple thing: say to a server from a client a simple message like "HelloWorld" but the client recieve as echo only first message as "HelloWorld". Other messages were empty.

I also tried "Fleck" (name of the websocket system) and there an echo work was ok.

What is can be causes of this problem?
I debbuged the sending routine and i really dont saw any different cases in the first\second message sending routine. Also if i close the connection and already open the connection - the next first message will be ok. Maybe some connections information somewhere marked as "dirty" and wait for some message from a client?
Also if that will usefull - messages from a client is ok always.
Also i've tried this case: client connected to a server, and the server send to a client what i wrote in the console. First message is always OK, next - empty.

Can you help me or give me some advice please? Thank you!

Start with the linked UE4Websocket samples and compare the first and subsequent message paths in the sending routine. Reproduce the echo behavior with the Unreal client and websocket-sharp, then determine why later server messages are empty; done means repeated messages are received correctly without reconnecting.