I managed to apply the same guidance by manually setting my Ethernet connection on the MAC (System Preferences, Network, Ethernet) and then manually configuring as follows:
Configure iPv4 (select Manually from drop down)
IP address: I used 192.168.1.199
Subnet Mask 255.255.255.0
I was then able to open up the router menu in Chrome and update the firmware from a previously downloaded file.