Comment 7 for bug 1287635

Here are a few more clues from the first apport file:

NetworkManager[1220]: <info> (eth1): new 802.11 WiFi device (driver: 'wl' ifindex: 3)

NetworkManager[1220]: <info> (eth1): deactivating device (reason 'managed') [2]

NetworkManager[1220]: <info> (eth1): device state change: disconnected -> unmanaged (reason 'removed') [30 10 36]

NetworkManager[1220]: <info> radio killswitch /sys/devices/pci0000:00/0000:00:1c.1/0000:04:00.0/ieee80211/phy0/rfkill1 disappeared

wpa_supplicant[1357]: Could not read interface eth1 flags: No such device

Apparently NetworkManager deactivates the device for some reason. I'm not familiar with NetworkManager, let's ask an expert.