Both the DCS/XLX and REF/XRF connectors exchange remote and local module information during connecting to the server, so this information is exchanged between the OS4 and the server. Its up to the server's dashboard to display this module information or not.
You can connect to the same server using both connectors if the server supports both protocols. If you can't find the REF/XRF server in the DCS/XLX connector's server dropdown list then enter the server address manually (make sure Advanced mode is enabled at the bottom right of the web interface to see the Server address entry).