When I connect to the WebViewer, I receive «Plug-in connection failed! (Network Error)» message.
In case the TCP Port is not opened or in case of certain SRN products without bandwidth designation may cause this warning message.
Check whether port forwarding or DMZ setting has closed ports at the router setting.
Use the site below the check whether a port is opened.
http://www.yougetsignal.com/tools/open-ports/