In cases where vCenter Server plug-ins are not working, you have several options to correct the problem.

vCenter Server plug-ins running on the tomcat server have extension.xml files which contain the URL where the corresponding Web application can be accessesed (files are located in C:\Program Files\VMware\Infrastructure\VirtualCenter Server\extensions). Extension installers populate these XML files using the DNS name for the machine.

Example from the stats extension.xml file: <url>https://SPULOV-XP-VM12.vmware.com:8443/statsreport/vicr.do</url>.

vCenter Server, plug-in servers, and the vSphere Clients that will use them must be located on systems under the same domain. If they are not, or the DNS of the plug-in server is changed, the plug-in clients will not be able to access the URL and the plug-in will not work.

You can edit the XML files manually by replacing the DNS name with an IP address. Re-register the plug-in after editing its extension.xml file.