Having recently purchased my second Android box, a M9C max (S905X, 2/16GB), I can report that Netflix runs great at 720p with the 8.90.4 alpha.
Apart from installing the Netflix plugin and widevine.sh, importing Cryptodome seemed also needed to fix a dependency error.
After this, Netflix ran at 720p, but barely watchable. Thankfully, I read a tip from Gismo112 in the Kodinerds forum on cache settings in advancedsettings.xml. With these, there hasn't been a single hiccup so far (with HEVC disabled in the Netflix settings)!
I have tried all sorts of movies and TV shows, with various frame and refresh rates, and am impressed with picture quality.
The quality is really much better compared to the Netflix app running on stock Android 6.0.1 that came with the box.
It is connected to a rather old 1080p Samsung 5-series TV. Dependent on the Netflix movie, it always displays 1080p, but at various refresh rates like 24, 50 or 60 Hz. Typing "o" on the wireless keyboard shows Netflix streaming at 720p. CPU usage is pretty high though, with one or more of the cores hitting 100% at times. Still, the picture plays flawlessly
Below's a log of what I did to get it working :
LibreELEC2:~ # wget getwidevine.sh
Connecting to nmacleod.com (212.23.8.80:80)
getwidevine.sh 100% |*******************************| 2130 0:00:00 ETA
LibreELEC2:~ # sh getwidevine.sh
Detected ARCH: arm
Download directory: /storage/.kodi/cdm
Downloading: libwidevinecdm.so for arm...
######################################################################### 100.0%
Successfully installed libwidevinecdm.so!
LibreELEC2:~ #
LibreELEC2:~ # python
Python 2.7.14 (default, Feb 13 2018, 01:44:00)
[GCC 7.3.0] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import Cryptodome
>>>
Add below data to the advancedsettings.xml in /storage/.kodi/userdata:
advancedsettings.xml:
<advancedsettings>
<cache>
<buffermode>1</buffermode>
<memorysize>157286400</memorysize>
<readfactor>20</readfactor>
</cache>
<loglevel>1</loglevel>
</advancedsettings>
LibreELEC2:~ # reboot