Firefox can transparently handle a change of network interfaces.
I would expect the same to be true for KDE Dolphin / plasma / vlc on kde.
See the scenario below to prevent duplication of information here.

- 
- Dolphin and the movie freeze.

Now I do service networking restart -> no effect.
After about two minutes both the movie and Dolphin simultaneously start working again.

But now the start menu (Lancelot) does not work anymore.
Wait a minute, the taskbar does not react anymore. The whole of plasma seems to be stuck...
Something within the innards of KDE is not right!
Luckily I can still type "reboot now" in a terminal.

To be honest, I did not expecte restarting networking to help.
I think the networking part itself works very good -> I can immediately
browse the internet with Firefox again. I suggest that it is a higher level subsystems (kio?) that cannot
handle switching the "network backends". When it times out it re-establishes a connection to
the networking subsystem again -> bingo.

Reproducible: Always

Steps to Reproduce:
1. Boot the laptop and start using wireless (no network cable connected),
2. Use Dolphin to select movie on NAS (CIFS or NFS makes no difference), movie starts in VLC
3.  connect 1GB network cable. Network manager shows the cable icon, BUT:
movie and Dolphin are still using wireless, so they do not switch to wired automatically
4. Use networkmanager plasmoid to stop the wireless networking

Actual Results:  
Dolphin hangs.
The movie hangs.
After a while the whole plasma desktop hangs. Cannot use start button, alt-f2, taskbar etc.

Expected Results:  
1. When I plugin the network cable I expect everything to switch to this faster connection.
2. At least, when I switch off the wireless, I expect KDE to use the wired connection.
    This should not bring KDE to a halt

To be able to use KDE in a normal office environment, docking / undocking should work.
And kde should not freeze if network connection is lost etc.
That's why I want to report this as a major.

I hope that I reported against the correct component.
My "analysis"
1. Network-manager seems to work all right (Switching network interfaces is not a problem
for kde). The only problem there seems that it does not automatically prefer wired over wireless.
2. Problem does not seem Dolphin-specific since the whole of kde is affected.
3. That's why I reported agains kio-network: it seems to be the common denominator of
   the affected KDE components.

Just tell me what other information you find useful.