Is APM Portal Webtop links possible to provide internal network links that doesn't require open Network Access?

So I'm preparing a deployment of APM as remote office solution, and wish to provide some internal website (such as Helpdesk portal, that requires internal network access to APM web portal, while APM users can directly access these websites without connection to internal network via Network Access tunnel.

I tried to add links directly via "Webtop Links" and assign to users, but it seems not working. When Network Access tunnel is not open, client device will access these links as if they just type the links in their browsers. Since these websites are internal website, client device cannot access these websites.

It seems the link is acting as a "bookmark" dedicated for APM users, without ability to access internal applications. Am I doing it in the wrong way? Kindly share your experiences during APM deployment, thanks!