New router no wireless w ethernet - Mac to Brother mfc-736

My printer is actually a Brother mfc-736 - before I upgraded my internet and got a new router last week, the printer connected to my wireless network via ethernet - and I could print remotely/ wirelessly from my Mac air. Now I can’t do that.

I have tried to reset the network on the printer - but it didn’t work and all the answers I have found online only relate to resetting a wireless connection - this old trusty printer is not wireless and ethernet has always been the work around.

Is there someone out there who knows what the problem might be? I read on an earlier thread (03/07/17 by vaidya “If you've recently switched from 2.4GHz to 5GHz wifi - this is the problem! Brother printers cannot connect to 5GHz wifi….” with a suggestion to request the internet provider “split the combined network into two separate networks, a 2.4GHz one and a 5GHz one - then connect your printer to the 2.4GHz!”

Is this what I need to look into? Not even sure this is an option. Can someone let me know if it is possibly to add this computer to my network via ethernet?