This has been solved. The issue and solution is in this post:

Previously I had my Brother 790CW printer running via wifi, but I would prefer to run it via a wired ethernet connection. I have a small LAN at home with my computers and printer connected to a switch. I can see the printer and IP address on the network using nmap. In the "Add New Printer" dialog box, it shows a box for IP address and "queue". Where do I get the information for the field "queue"?

Thank you.

System info:
Operating System: KDE neon 5.18
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.69.0
Qt Version: 5.14.2
Kernel Version: 5.3.0-51-generic
OS Type: 64-bit

Solution:
Make sure you install both the LPD and Cupswrapper drivers here:
https://support.brother.com/g/b/downloa ... all&os=128

Then you need to follow the instructions here very carefully:

https://support.brother.com/g/b/downloa ... &type3=561

In particular, you need to follow the network connection terminal commands and use http://localhost:631/admin.

Solved, refer to first post.

Great post, a lot of stuff in here i did not know about