Comment 31 for bug 69118

It seems I managed to solve this problem. If kwalletmanager starts before knetworkmanager, things seem to be OK.
So I created a file /usr/share/autostart/kwalletmanager.desktop, which starts after panel

[Desktop Entry]
Encoding=UTF-8
Name=kwalletmanager
GenericName=Wallet Manager
Exec=kwalletmanager
Icon=network
Type=Application
X-KDE-autostart-after=panel
X-KDE-StartupNotify=false
X-KDE-UniqueApplet=true
X-DCOP-ServiceType=Unique
X-KDE-autostart-condition=kwalletrc:General:Autostart:true
Categories=Qt;KDE;Network;Applet;
X-Ubuntu-Gettext-Domain=desktop_kwalletmanager

 and I modified knetworkmanager.desktop such that it starts after kwalletmanager.desktop:
X-KDE-autostart-after=kwalletmanager

Most probably simply modifying knetworkmanager.desktop would also help (not tested...)
Exec=kwalletmanager; knetworkmanager