Thanks for your continuing interest!
In Session and Startup > Application Autostart, I do have an entry "Network (Manage your network connections)".
It is selected & is not editable.
On my same PC, I still have 12.04LTS as lifebelt & that continues to show the Network applet correctly.
I looked in /etc/xdg/autostart & found an item called "network".
The content is similar, but not identical to the item "nm-applet" in 14.04 - see below.
Code:
12.04 Network:
[Desktop Entry]
Name=Network
Comment=Manage your network connections
Icon=nm-device-wireless
Exec=nm-applet
Terminal=false
Type=Application
NoDisplay=true
NotShowIn=KDE;
X-GNOME-Bugzilla-Bugzilla=GNOME
X-GNOME-Bugzilla-Product=NetworkManager
X-GNOME-Bugzilla-Component=general
X-GNOME-Autostart-enabled=true
X-Ubuntu-Gettext-Domain=nm-applet
Code:
14.04 nm-applet:
[Desktop Entry]
Name=Network
Comment=Manage your network connections
Icon=nm-device-wireless
Exec=nm-applet
Terminal=false
Type=Application
NoDisplay=true
NotShowIn=KDE;
X-GNOME-Bugzilla-Bugzilla=GNOME
X-GNOME-Bugzilla-Product=NetworkManager
X-GNOME-Bugzilla-Component=nm-applet
X-GNOME-UsesNotifications=true
AutostartCondition=GNOME3 unless-session gnome
X-Ubuntu-Gettext-Domain=nm-applet
I tried launching nm-applet directly, by double-clicking on it in etc/xdg/autostart, and got the following warning:

When I clicked on "Launch anyway", nothing happened...
If I open etc/xdg/autostart as Root & double-click on nm-applet, I get the same message, but if I then click to Launch anyway, then the applet appears as required...
That is as far as I can get...