Hello,
There is no way for the .NET client to use the JS protocol. Why would you want to do that?
The .NET client should use http-streaming but may resort to polling if the streaming connection seem not to be working. The JavaScript client would do the same. See
http://www.lightstreamer.com/distros/Lightstreamer_Allegro-Presto-Vivace_5_1_2_Colosseo_20140722/Lightstreamer/DOCS-SDKs/sdk_client_dotnet/doc/API-reference/Lightstreamer_DotNet_Client_LSClient_OpenConnection@ConnectionInfo@IConnectionListener.html
Are you testing the client against our server or your own? Do you have some kind of proxy in the middle?