You know, you reminded me when I bought a DM and found a huge difference between it and my other device.
My first problem was that I couldn't turn the AC3 volume up or down.
Something as basic as that I couldn't do! and I found that this is normal and not a problem that needs to be fixed!
Really, I was disappointed because I didn't expect that despite the power of the hardware, I didn't find enough professional support.
I also found some basic features that didn't work at all and work well with other competing devices.
And most of the plugins available in the feed are very old and stopped working long time ago and not updated yet, such as YouTube, Weather...
And you need to wait for a long time (up to years) for plugins to update or fix some problems.
Also the UI which looks unattractive, and all available skins didn't work well.
Now I only use the device to watch encrypted channels and follow sporting events.
Other than that, I use my other device (Humax Aura 4K) to watch shows, movies, and series, it has excellent hardware, better user interface, continuously updated apps, and all features work well.
Sorry for saying that, but this is what I found when I used the DM.