I have mobile usb modem huawei E1750.
It is known that mageia network center has problem with this modem.
But knetworkmanager manages to connect my modem into internet because I see it on modem signalization.
However firefox refers me that there is not network available, the same updates, software center, ...
It seems although I am connected via knetworkmanager, other parts of mageia system do not know it.
This is problem in Mageia 1 and also prepared Mageia 2. And the only reason for what I do not use mageia although I like it.
For example Kubuntu, openSuse, Fedora, Debian Kde do not have this problem.