I think since 5.5 the configuration icon has been missing from the Connect menu of the NM applet The button is there, but no icon (and there's no visual indication of the button without hovering over it) I've attached two pictures that show the issue Reproducible: Always
Created attachment 96589 [details] The menu
Created attachment 96590 [details] Hovering over the button
Try to update to latest frameworks, kill plasmashell, clear $HOME/.cache/ directory and then run kbuildsycoca5 and start plasmashell again.
I didn't update, but did the rest. That solved the problem.
Bulk transfer as requested in T17796