Mobile Broadband neglects USB Ethernet WAN

[Michael Titke]

I usually connect my smartphone to my Mac via USB.

Some years ago I discovered (still on Mac OS X) that in addition to the usual dial-up connection of my smartphone attached to my Mac there was a WAN connection on the same device with an IP-adress. I sent a ping on it but no response. At some point later in time that WAN connection became active as soon as I attached the smartphone to my Mac and I was connected to the Internet without any dial-up / PPP but with an ethernet/WAN style connection.
 From then on when I wanted to connect to the Internet I just attached the smartphone via USB.

Now I am on Ubuntu 15.04 (with network-manager 0.9.10.0-4ubuntu15) and when I attach my smartphone I see the following behaviour of the network-manger:
1) the ususal Ethernet connection as soon as the smartphone is attached and then my smartphone connects to the Internet
2) something neglects that Ethernet connection and brings it down - I can't find it anymore
3) with my smartphone still connected to the internet I can tell the network manager to use my mobile broadband via dial-up
4) it dials up and my smartphone somehow converge this with the existing connection to the Internet
5) now I can use the Internet from within Ubuntu on my Mac

My provider currently is O2 Deutschland / Telefonica Germany and I have a prepaid flatrate.

The described behavior works reasonably well but I do see that something neglects the plug&surf wan/ethernet connection. This may be different for each and every combination of provider, data plan and smartphone but perhaps it would be possible to investigate this issue to allow for that easy plug&surf behavior again.

Thank you!

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: network-manager 0.9.10.0-4ubuntu15
ProcVersionSignature: Ubuntu 3.19.0-15.15-generic 3.19.3
Uname: Linux 3.19.0-15-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Jun 11 10:58:44 2015
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2015-06-08 (2 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
IpRoute:
 default via 10.64.64.64 dev ppp0 proto static metric 1024
 10.64.64.64 dev ppp0 proto kernel scope link src 10.168.134.166
 169.254.0.0/16 dev ppp0 scope link metric 1000
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
RfKill:
 0: hci0: Bluetooth
  Soft blocked: no
  Hard blocked: no
SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH CONNECTION CON-UUID CON-PATH
 ttyACM3 gsm connected /org/freedesktop/NetworkManager/Devices/6 O2 LOOP 549191f7-e838-4842-9315-d54d07b9a0ba /org/freedesktop/NetworkManager/ActiveConnection/4
 ppp0 unknown connected /org/freedesktop/NetworkManager/Devices/7 ppp0 0f774378-0fc3-484d-9476-1ada08a3138d /org/freedesktop/NetworkManager/ActiveConnection/5
 eth0 ethernet unavailable /org/freedesktop/NetworkManager/Devices/1 -- -- --
 lo loopback unmanaged /org/freedesktop/NetworkManager/Devices/0 -- -- --
nmcli-nm: Error: command ['nmcli', '-f', 'all', 'nm'] failed with exit code 2: Error: Object 'nm' is unknown, try 'nmcli help'.