I'm using ESXi 6.5, access through the web to manage, but I installed a client, the vSphere client, I know that after the 5.5 all the administration will be through the vSphere Web Client, but is there a pluggin?
The old thick/fat/C#/desktop client does not work with ESXi 6.5 after Update 1. You will have to use the embedded host client through a web browser at https://<fqdn>/ui.