and why is it virtually impossible to bring back up?
had wireless set-up and working, connected to a network.
but network connection timed out and would not reconnect, so i clicked on the knetworkmanager icon to open the dialogue box, and then clicked on the enable wireless icon with the intention of unticking it, and then reticking it to see if that ‘solved’ the problem.
instead, the knetworkmanager icon disappeared, and then could not be restarted.
a technical friend who runs complex gentoo networks for a living eventually managed to restart various bits-n-bobs and get knetworkmanager running again, but…
… why did it disappear in the first place?
and why was it not easily restartable from the icon?
friends didn’t really know what had gone wrong, but seemed to think it was related to a security policy.
I think the only way to know what happened is look through the logs (/var/log/NetworkManager). It certainly shouldn’t behave that way and as far as I know this is not related to any security policy. The easiest way to restart is run “/etc/init.d/network restart”.
The other thing You might try is use plasmoid network management instead of knetworkmanager (don’t know if You’re using KDE even ) but this step is only sensible if the behavior is reproducible.
There are others that prefer to use the gnome NetworkManager applet but the plasmoid and knetworkmanager work great for me so I don’t see a reason why they shouldn’t work for You.
When you unchecked the “Enable Wireless” box you disabled Networking Services… And I think you can probably guess what that might mean to a Network Manager managing networking…
What you <really> should do is when you lose network connectivity to instead click on the listed connection.
That initiates a new attempt to re-establish a connection with your wireless gateway (is comparable to a ipconfig /renew in Windows)
all without turning your network services off.
You might notice also that if you have multiple connections listed it means that Network Manager recognizes you have valid configured credentials for each of those, if you want to change connections just click on that other connection.
Back when running 11.3, I had an occasion where knetworkmanager told me that I was connected, but no packets were getting out. So I unchecked “Enable Wireless”, waited a few seconds, checked it again. And knetworkmanager disconnected and reconnected, thereby reestablishing my connection.
I could not find another way to get that result (other than rebooting).
Clicking on “Enable Wireless” certainly should not close down knetworkmanager and its task tray icon, nor too should it make it impossible to restart knetworkmanager.
) but this step is only sensible if the behavior is reproducible.