That was the second thing I tried (first was swapping network cables).
Wired network is working in LibreElec 8.0.1 installed in a NUC6CAYH with "Wireless networks enabled", no NTP server configured, "Wait for network before starting Kodi", with 10 seconds timeout (translation from Spanish menu options). Wireless enabled but not connected -> wired network also works.
My gigabit network setup: NUC -> Conceptronic 8 port hub -> Asus RT-AC66U <- File server
PS: Bios v0038, perhaps BIOS configuration could affect. Main BIOS setup change: "Linux" option selected under OS configuration menu.