Re: NetworkManager will not save passwords, KDE control module error "Did not receive a reply".
You will need to tell us which desktop you are using.
The applet used for accessing NetworkManager settings is different for KDE and Gnome. Most other desktops are probably using the Gnome applet.
openSUSE Leap 15.4 Beta; KDE Plasma 5.24.4;
testing Tumbleweed.