We have an HMI with connections on the back. When a person unplugs the ethernet cord a built-in popup will show this:

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Gateway Connection Lost

Gateway is not available http://link

Unable to connect to Gateway http://address : no route to host: getsockopt

Searching for active Gateway

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With this warning message the operator is able to bypass the client session and get to the HMIs Windows desktop. By selecting this Gateway link on the popup, the built-in web app will try to connect to the link.

There isn't a way to make this Gateway address un-linkable so the user will stay in the client.