[skagass]

I think you mean the S905X MECOOL M8S Pro + which has pretty poor 2.4GHz only b/g/n WiFi
The MECOOL M8S Pro is a S912 where LibreELEC does not work properly.

Refresh switching is broken in the Mi Box, as I said use it for Android TV Apps only. Not demanding Kodi use.

Boxes with known working AC WiFi are already listed in here:

AMLogic S905(x) - LibreELEC / OSMC - Kodi Krypton - 4K Options:

The AP6255 AC WiFi Chip (same as Wetek Hub) in the 2GB/16GB S905X Khadas Vim's would work as well with LibreELEC Kodi Krypton using @kszaq's LE 8.2 image. (See LibreELEC forums.)

If you wanted Optical on that device you would need to add a HDMI > SPDIF Audio extractor as suggested by @noggin. You may need to Spoof 5.1 AC3/DTS audio via some sort of Audio extractor switch. We really are not sure.

Or you could buy an all in one Vero 4K where you are guaranteed everything will work.

If you do not need HDR buy a S905 MINIX U1 with its superior MIMO AC WIFi and SPDIF. Its integrated Wireless A2 lite remote is excellent.
Great device for 4K LibreELEC.

Sorry if hijack this post, what about 912s models? Are they still just bad, as written in the first post? Hasn't libreelec made some progress on them?

I'm undecided between a Mi Box 3 and a H96 PRO+ 3gb/32gb (cost is the same, ~ 60 €)

I need them for kodi and iptv on a fhd tv, what would you suggest?