Universal Media Server | Forum

They are supported, but with some limitations. First, I don't think the ISO can be encrypted (although I'm not 100% sure of this). Second, MPlayer must be available and working (bundled on Windows and macOS, must be installed manually on Linux). Third, the MPlayer output must be acceptable for the renderer (The output isn't 100% to spec, so a very few will complain/refuse to play AFAICR).

It seems UMS doesn't have a "renderer configuration" for your renderer - which means that it will just send any file as-is without doing any transcoding. That will only work for files supported by the renderer, and ISO files obviously aren't among those.

You need to find or create a renderer configuration for your renderer. There's no easy way to do this, you need to search the forum and read some of all the explanations already posted - if you're lucky you'll find one that will work or that can just be tweaked slightly.

Yes, any files that are natively supported by the renderer will still work - like for example "normal" MPEG files. Anything that ISN'T supported by the renderer must be converted/transcoded, like for example ISO files, and that's where the "renderer configuration" is needed to tell UMS what formats/codecs are and are not supported. Without such a configuration, UMS simply assumes that "everything" is supported, even though I very much doubt such a device exists

It's hard to say without a full log, but I wouldn't be surprised if that was caused by it not being "recognized" as well.