sandin can you test with the latest Milhouse build libreelec-generic.x86_64-9.0-milhouse-20181201210245-#1201-g5dc77c9.tar ?
With this build wifi should work out of the box and it also includes a fix for firmware handling, overriding/adding firmwares via /storage/.config/firmware should now work in all cases (also for bluetooth / hciattach firmwares).
so long,
Hias