Network connection breaks down regularly

[Wolf Rogner]

Using WiFi on all my notebooks the network connection terminates at random (no signal, no connection).

Reconnecting to the AP does not work (connection efforts take endlessly).

Disabling and Re-enabling Wireless Network works immediately.

This used to be an issue on a Macbook Pro Retina 15" at first, later the MBPR13" had the same issue and finally my old HP 8510w does the same.

No regular events in the neighborhood (APs comming up or going down) or in PC workload.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: network-manager 0.9.8.8-0ubuntu7
ProcVersionSignature: Ubuntu 3.13.0-36.63-generic 3.13.11.6
Uname: Linux 3.13.0-36-generic x86_64
NonfreeKernelModules: nvidia wl
ApportVersion: 2.14.1-0ubuntu3.4
Architecture: amd64
CurrentDesktop: Unity
Date: Wed Sep 10 10:37:33 2014
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2013-05-17 (480 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64+mac (20130424)
IpRoute:
 default via 10.1.0.254 dev wlan0 proto static
 10.0.0.0/8 dev wlan0 proto kernel scope link src 10.1.0.103 metric 9
 192.168.97.0/24 dev vmnet8 proto kernel scope link src 192.168.97.1
 192.168.204.0/24 dev vmnet1 proto kernel scope link src 192.168.204.1
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
SourcePackage: network-manager
UpgradeStatus: Upgraded to trusty on 2014-04-20 (143 days ago)
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH
 wlan0 802-11-wireless connected /org/freedesktop/NetworkManager/Devices/0
nmcli-nm:
 RUNNING VERSION STATE NET-ENABLED WIFI-HARDWARE WIFI WWAN-HARDWARE WWAN
 running 0.9.8.8 connected enabled enabled enabled enabled enabled