Just thought I'd add that I'm seeing the same error - 'failed to register plugin' but with no further explanation. I'm using vCentre 5.0. The appliance seemed to deploy OK, I can ping it and get to the web console and I've tried using both FQDN and IP of vCenter with no luck. Looking at the log file /logs/supportassistant.log shows a bunch of DEBUG statements and one ERROR statement (NOTE I've changed the IP for security);
2013-01-29 17:50:36,375 INFO com.vmware.gss.phonehome.util.PhoneHomePluginRegister - registerPlugin() ----> pluginKey = [com.vmware.supportassistant], pluginConfigUrl = [https://10.x.y.59/plugin-config.xml]
2013-01-29 17:50:41,616 ERROR com.vmware.gss.phonehome.util.PhoneHomePluginRegister - Can't register plugin
com.sun.xml.ws.client.ClientTransportException: HTTP transport error: java.net.NoRouteToHostException: No route to host
From the name I'm guessing the appliance is trying to 'phone home' and if that fails the plugin fails to register. I'm using a proxy which needs authentication and despite entering a username/password at the network configuration stage (which I've checked with configure-network) I'm guessing that fails. Is there anyway to dig further? The network diagnostic tests are done within the plugin so it's a catch-22 situation.
Regards,
Ed.