KDE is so widely used and supported that there is usually more than one utility to do any given task. However, there is usually an official tool and then alternatives.
For managing networks, especially wireless and bluetooth networks, the knetworkmanager utility is the official tool to use. However, although knetworkmanager is very promising and integrates nicely into the KDE bar and is well designed and thought out, at present it seems to not be able to handle WEP encryption very well. Many people have reported problems with knetworkmanager whereas other network managers work well with the same settings on the same wireless network and hardware.
We tested knetworkmanager with kubuntu Heron and a 10 character ASCII WEP key. While WiFI Radar worked well, connected immediately and scanned the range of wifi networks accurately, on the same laptop (Dell XPS M1730) knetworkmanager simply was unable to connect to the same WiFI connection that WiFI Radar connected to. We ensured that kwallet had the correct key in it and to make extra sure we also tested in the config file mode that knetworkmanager offers (storing the WEP passphrase in unencrypted text format).
In /var/log/syslog there were numerous lines with the following entries:
wlan0: RX authentication from XX:XX:XX:XX:XX:XX (alg=1 transaction=4 status=15)
wlan0: unexpected authentication frame (alg=1 transaction=2)
wlan0: replying to auth challenge
wlan0: authentication with AP XX:XX:XX:XX:XX:XX timed out
It seems that for some reason, whilst other network management tools are able to configure the WEP passphrase correctly, KNetworkManager cannot. However, when we tested on unprotected WiFI networks, KNetworkManager worked a treat, reinforcing the notion that it only struggles with encryption.
We also discovered during testing that sometimes other WiFI tools such as WiFI Radar scanned and reported more WiFI networks in the same area with the same laptop at the same time than KNetworkManager did. To be fair, we tried several scanning interations, starting up WiFI Radar and then KNetworkManager alternatively to ensure that the laptop hardware could still see all the WiFIs in the area. Not only was WiFI Radar consistent in its reports, but KNetworkManager was inconsistent, sometimes reporting the same number of WiFI networks as WiFI Radar, other times not seeing several of the networks.
Browsing around the 'net, it seems that some people have KNetworkManager working and others do not. So at least part of KNetworkManager is functional, however if you are roaming networks and encounter a wide range of passphrases and WiFI configurations, this means that for now, KNetworkManager is practically unusable.
So for now, it seems that unfortunately the KDE default network management tool should not be used. Instead, we would recommend that you try other tools. We found WiFI Radar to be excellent.However other tools are also available.