If you need to run GcHtmlBrowser on Windows 7, you can use WebSocketFactory to inject System.Net.WebSockets.Client.Managed.

WebSocketFactory = async (uri) =>
{
    var client = SystemClientWebSocket.CreateClientWebSocket();
    if (client is System.Net.WebSockets.Managed.ClientWebSocket managed)
    {
        managed.Options.KeepAliveInterval = TimeSpan.FromSeconds(0);
        await managed.ConnectAsync(uri, default);
    }
    else
    {
        var coreSocket = client as ClientWebSocket;
        coreSocket.Options.KeepAliveInterval = TimeSpan.FromSeconds(0);
        await coreSocket.ConnectAsync(uri, default);
    }
    return client;
}