In cases were vCenter Server extensions are not working, you have several options to correct the problem.

vCenter Server extensions 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, extension 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 extension server is changed, the extension clients will not be able to access the URL and the extension will not work.

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