In addition to the document you linked to, you may want to review this other documentation: http://techdocs.zebra.com/link-os/2-14/webservices/content/link-os-pg-addendum-en.pdf which details how to configure the printer to connect to your server.
Please note that in this type of configuration, the WebSockets connection originates in the printer and targets your .Net (or other) server. Your server will receive an HTTP request from the printer and is responsible for upgrading that connection to a websocket (and keeping it open). Once the connection is established, your server can send print commands to the printer through that connection.
Does that help?
Technical Architect, Kutir Mobility
Posted on behalf of Zebra Technologies