Welcome!
I think there might be several possibilities.
1. The NIC (network interface controller) might not be supported, thus no way to communicate with your DHCP server to obtain an IP address. Select Option 9 to enter the root shell and provide output of the following commands and/or otherwise provide details of the NIC hardware.
Code:
lspci (if PCI NIC)
usbconfig (if USB NIC)
ifconfig
dmesg
2. LAN cable is disconnected and/or bad
3. You don't have a DHCP server set up on your LAN, thus you will have to manually set a static IP address, netmask, gateway via Option 1