At moment only a few apps are designed to be Reachable over Web out of the Box. The apps can be manually made reachable over web, but this requires a crawl through config Files that maybe lead to the problem, that something is broken by accident. A button at the app in the backend that enables the feature that the app is reachable out of the internet by e.g. cpg.yourhda.com/fooapp would help to solve that problem.
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