The ESXi host must limit the number of concurrent sessions to ten for all accounts and/or account types by enabling lockdown mode.

Enabling lockdown mode disables direct access to an ESXi host requiring the host be managed remotely from vCenter Server. This is done to ensure the roles and access controls implemented in vCenter are always enforced and users cannot bypass them by logging into a host directly. By forcing all interaction to occur through vCenter Server, the risk of someone inadvertently attaining elevated privileges or performing tasks that are not properly audited is greatly reduced.