Hi
Another common issue about the plugin can not connect Serengeti server is that the Serengeti management server didn't enable the SSO. The plugin and Serengeti server need use the same SSO service to do the authentication.
If you miss the step to set the SSO lookup service url when deploying the Serengeti virtual appliance. You need to login Serengeti management server, go to the /opt/serengeti/ssotool directory, perform the command "EnableSSOAuth <vc sso lookup service url> " After the command finished, you need restart the tomcat service to make it work.
By default the vc sso lookup service url is https://<vc-server-ip>:7444/lookupservice/sdk, you need to make sure the Serengeti server and vSphere web client use the same SSO service.