The Raspberry Pi 4B has both wired and wireless ethernet. To use the wired connection for a Mesa Ethernet card you need to setup a static IP address and use the WiFi connection to ssh into the Rpi4.
To get a list all available WiFi networks
sudo iwlist wlan0 scan
Configure the WiFi SSID and Password
Then get the broadcast address of the WiFi
wlan0 is what you’re looking for, note the inet address is the one you use to SSH from another PC into the RPi4.
wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 inet 192.168.1.67 netmask 255.255.255.0 broadcast 192.168.1.255
From another PC you can SSH into the Rpi with the inet address like this
To setup the static IP for eth0
sudo nano /etc/dhcpcd.conf
At the bottom of the file is an example for setting up static IP. Change the eth0 lines to match this
interface eth0 static ip_address=10.10.10.11/24
Ctrl X, Y, Enter to save your changes.
Now reboot so the changes take effect.
A good tool to scan your LAN is Angry IP Scanner
Updated Aug 23, 2019