What they write here seems to be a complete nonense: Hostname Setting · libretro/Lakka-LibreELEC Wiki · GitHub
LibreELEC-beni:~ # echo "LibreELEC" > /storage/.cache/hostname
LibreELEC-beni:~ # reboot
LibreELEC (official): 8.2.5 (RPi2.arm)
So the name is still "LibreELEC-beni"... WTF??
Change it in both /storage/.cache/hostname and /etc/hosts does also not solve my problem.