I installed 11.2 and KDE 4 on a laptop last night and had some issues with knetworkmanager for which I did not find a quick answer here but eventually figured it out so might help some others:
knetworkmanger by default wants to use Kwallet, if you disabled kwallet then knetworkmanger will not connect anymore. You need to re-enable kwallet again in personal settings, advanced or configure knetworkmanger to not use kwallet (see next tip)
knetworkmanger can work fine without kwallet if you go to the settings and select to store the secrects in a file.
if for some reason knetworkmanger wont start by itself go to ~/kde4/share/config and open networkmanagentrc with kwrite and make sure autostart=true
it’s working for me even with the wallet disabled, but i did update it after install, enabling the traditional if-up networking to do the update then switching back to networkmanager afterward.
i do have a question about it though whille i am here. it works fine with my wireless but with my mobile broadband (Cricket USB) if i disconnect or if the connection is dropped, i can’t reconnect without rebooting. any ideas?
also even though there are provisions in the System Notificans to handle network-generated events, they don’t seem to fire when using the knetworkmanager applet.