With the latest version(s) of VMware ESXi, 6 and 6.5, VMware decided it would be most convenient to automatically logoff sessions every 15 minutes. So, after 15 minutes of inactivity, you have to log back in to the ESXi Host Client Web Interface, again and again. I found this extremely annoying. Especially in a lab environment when testing various features or troubleshooting issues. Fortunately, this automatic logoff timeout can be increased so it’s not quite so painful.
How to Increase Session Timeout on ESXi 6 & 6.5
To increase the session timeout, all you need to do is change one advanced configuration parameter in the ESXi Host Client Web Interface.
First, log in to the web interface. After doing so, navigate to Host > Manage > System > Advanced Settings. Scroll down or search for the UserVars.HostClient.SessionTimeout key.
The default value for UserVars.HostClient.SessionTimeout is 900. Because this value is in seconds, by default you will be logged out after 15 minutes of activity. Personally, I would like to set this to 24 hours, but that isn’t possible.