until further notice on Fire TV unusable ...

Actually, a well-crafted library in terms of operation and clarity. With my Fire TV, which wired the internet with max. 32 Mbit / s is on the way, and streaming broadcasts should be no problem. But are apparently also at ZDF, as indeed in the ARD, the server is busy quickly. So the program start to hang sometimes after only a few minutes to reload. Unfortunately, this does not remain the only problem, it seems to just that one is completely thrown out of the currently loaded program, although this has been going on longer.
Because suddenly he says something like this: "... can not be loaded in the region" or "... currently is not available".

Sadly, even the ZDF media library app thus remains unusable in addition to the ARD library app. Whether that is now up to the apps on the Fire TV or I suspect the poor delivery of content by ARD and ZDF itself .... the result remains the same: Terrible.