Have run nm-connection-editor and looked there? I'm not sure what network settings you're exactly talking about, but that's the Network Manager manager.
In my experience, upgrades never go smoothly. I highly recommend saving your data and config setttings files and doing a clean install.
That might be an option if I didn't have SO many programs installed - from development utilities to sound editors and analysis to some others, it takes me a couple of days to get back to "normal" if I do a clean install instead of an upgrade.
I thought I saw a post a few years ago about saving your installed progs list from the apt-get cache, and using that for a new install. Anyone else know about that?
That's one of the reasons that I run Debian sid. Frequent little upgrades instead of big ones every 6mo. Occasionally there's some breakage, but having apt-listbugs installed usually lets me avoid that.
My test install of sid has been going very well, but I'm starting to get cold feet about upgrading to Debian when the time comes :^D I'm gonna upgrade Ubuntu anyway just to see how it works, and then install Xfce. If nothing breaks, and I like what I see, I may stick with it to avoid completely redoing my setup.
Anyway, the point is sid's pretty easy to get along with, but you have to pay attention when you get updates. Blindly hitting the install button likely won't give the best experience.