Hi I use Z77. I use ASRock Z77 Extermr4 board and BCM57781 LAN (Onboard). It was ok until High Sierra. But after install High Sierra, The onboard LAN keeps disappearing. It does not seem to have LAN at all. On linux, lspci, on windows, device manager and on mac lspci/ioregistryexplorer.... There's no lan. The only way to get it back is the CMOS reset. (Not a bios lload default menu, H/W jumper clear). I wonder if others have this problem.