Hi @frankygmail ,
If you are using the Windows client like below, you should be aware that this is no longer supported. That is why it isn't working. See the below blogpost:
https://blogs.vmware.com/vsphere/2016/05/goodbye-vsphere-client-for-windows-c-hello-html5.html
Furthermore, you should use the HTML5 client. Just go to the IP address in your browser. From there on you should be able to login to the ESXi host.
Visit my blog at https://vcloudvision.com!
