ventura system settings network settings submenu missing (the actual network settings pane is blank)

Thanks for confirming that method. I was aware of the possibility but I did not try it because I feared the unknown results. And because the support person I previously spoke with did not mention it.

What about wifi? There are 2 places in Settings that show wifi details. In the left pane one is located above the Network settings and if I click details I get nothing. I presume if I follow through with creating a "WiFi 2" then the Network panel will populate and so will the WiFi details.

This did not work for me as expected. When I create a new service for ethernet I get new parameters, thus I have to input all of my existing parameters since I am using a static IP. If I was using dhcp it would not matter. I would have to disable the current ethernet connection so there is no duplicate IP.

Creating a new service for Wi-Fi merely duplicates the existing Wi-Fi button. In below screenshot, creating a new Wi-Fi service in the right panel duplicates the info that already exists under Wi-Fi button in the left panel (above bluetooth button). And neither panel will work when I open it and click 'details'. All this said, this method is useful if you are uncomfortable using networksetup in terminal mode.

No. I spent quite a bit of time on the phone with support, tried lots of different stuff, including full reinstall of Ventura, various recovery techniques, etc. At the end he suggested I backup to time machine (which I already do) and wipe my partition on the SDD and return to whatever it is that Apple calls a fresh install from whatever is installed when my SDD shipped. I presume that means I'll have Yosemite. Then I am supposed to restore TM. I'm not confident in a full restore plus my TM is on an external NAS on a different network segment. I would feel better if I was using a usb directly on my machine. Finally, I would have to do macOS updates, not clear to me if I have to do each one or if I can jump immediately to the latest and less than greatest.

You can use the terminal cli app and run networksetup with the appropriate options to view & change settings. For example "networksetup -getinfo ethernet" where ethernet is the name of my ethernet connection.

I'm considering taking my entire desktop to the local 'genius bar' and seeing what they say. Hopefully they may have input to the developers.

Answering my own question, after a lot of digging, the answer is 'location'. Although the technique used by @timsidtim works I had problems with both static IP on ethernet and the Wi-Fi settings so it is not the best solution for my situation.

Apple menu  -> Location works well for me. Under submenu Network I edited the Locations by choosing the pop-up menu below the list of services (the 3 dots). Although I still had to input my settings I was able to do that very easily and the Wi-Fi dialog opened for input when clicking 'details', something that did not work for me using the 'add service' method.

I wonder what will happen if Apple ever fixes this and then there are 2 interfaces. I guess the next step is to delete interface #1.

Ok, guess I'll dive into the pond.