I've noticed my network
01:00.0 Ethernet controller: Broadcom Limited NetLink BCM57780 Gigabit Ethernet PCIe (rev 01)
is not recognized if I boot with the live media 17.0.5.
I have Manjaro installed and it is fine on the installed version but I recently tried the live media and didnt have the wired ethernet.
Note that Kubuntu 17.04 live has no issue with it either.
See here about the specificities of this card: