I have a Q-Box too, I didn't use this device tree and used the default one. I'll try this and see if it works better (I have random freezes at boot).
Why don't you install LibreElec to NAND by the way? Is it because you really need to have a browser on the box and need to access Android?
Haven't yet installed it to NAND because I thought to test a bit more, but so far it works quite well booting from USB.
This device tree thing is confusing. I only tried the gxbb_p200_2G_1Gbit.dtb one, which was a bit of a gamble as I haven't opened the devive to check in detail what chips are used. I purchased the q-box from Amazon, and according to the specs it should have an S905 and 1Gbit LAN port. Still not sure about the WIFI chip used, but tested WIFI and it works fine.
I haven't found much reliable info on the internals of these Q-boxes. But I'm impressed with what you get for the money. The performance is much better then my old AMD based HTPC. But that one has 5.1 audio, and for the Q-box I ordered a separate USB 5.1 audio interface. That should arrive tomorrow, curious how things will work.
Funny thing is that on a packaging-label it states Android 5.1, but the device came with Android 6.01 and Kodi Jarvis 16.1 preinstalled. Didn't work well intially, had to delete a lot of annoying apps and reinstall Kodi...