Kerry Jiang

Actually your receive filter base on SuperSocket 1.6 was implemented incorrectly.

Do you have any specification for your protocol or package format?

That's strange. The communication mode in your system is working in a special way, so how you implement the protocol doesn't matter.

Which version of SuperSocket do you use?

Thats strange. Beta 15 has nothing code change. The only change is adding more target frameworks.

Probably you should upgrade to the latest version of v1.6.

It looks like the connection dropped when the server was accepting it. Probably the preview version suppressed this error.

At that moment, you have no way to access http header because the connection was not accepted.

SuperSocket doesn't limit this usage.

You can use HandshakeValidator: https://github.com/kerryjiang/SuperSocket/blob/07d5a6f86601cbb7c76b2f18503103b3b232aede/test/SuperSocket.Tests/WebSocket/WebSocketBasicTest.cs#L163C103-L163C103