• confirm

ifconfig -a

may include something like this

eth0: flags=4098<BROADCAST,MULTICAST>  mtu 1500
        ether b8:27:eb:2c:94:19  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

or do

sudo service dhcpcd status

and you'll have something like this

systemd[1]: Starting dhcpcd on all interfaces...
dhcpcd[330]: Not running dhcpcd because /etc/network/interfaces
dhcpcd[330]: defines some interfaces that will use a
dhcpcd[330]: DHCP client or static address
systemd[1]: dhcpcd.service: Control process exited, code=exited status=6
systemd[1]: Failed to start dhcpcd on all interfaces.
systemd[1]: dhcpcd.service: Unit entered failed state.
systemd[1]: dhcpcd.service: Failed with result 'exit-code'.

• inject

ifconfig eth0 192.168.1.66 <or some appropriate number on the dhcp network>

• adjust dhcp via /etc/dhcpcd.conf

static domain_name_servers=172.24.1.1 192.168.1.1

Or via /etc/dhcp/dhclient.conf with this entry

option domain-name-servers 172.24.1.1, 192.168.1.1, 8.8.8.8

Adjust the latter according to the appropriate number for the eth0 network.

• confirm

hostname -I

If these conditions obtain:

• booting for the first time on this hardware
• using the Raspian OS upgraded on Raspberry Pi 3 Model B (without the +)

then it's likely that the boot disk doesn't contain the requisite firmware. So upgrade NOOBS.

• Download this NOOBS version
• mount 1 partition of the SD card

sudo mkdir -p /media/pi/MMC_P1
sudo mount -t vfat /dev/mmcblk0p1 /media/pi/MMC_P1

• delete contents of partition 1

sudo find /media/pi/MMC_P1 -mindepth 1 -delete

• unzip NOOBS into partition 1

sudo unzip /home/pi/NOOBS_v2_7_0.zip -d /media/pi/MMC_P1

• remove runinstaller
• sudo nano /media/pi/MMC_P1/recovery.cmdline

With runinstaller removed, the line should look like this

quiet ramdisk_size=32768 root=/dev/ram0 init=/init vt.cur_default=1 elevator=deadline

• shutdown

• "Update NOOBS without Re-Installing It (When Your Raspberry Pi 3B+ Will Not Boot!)"
• Using an SD card from PI 3 MODEL B in PI 3 MODEL B+