WWAN card connection failed if ipv6 is enabled

[Jan Kozusznik]

I installed WWAN card to a laptop and there was problem with connection. After debugging, I found that it crash on event “failed to open '/proc/sys/net/ipv6/conf/cdc-wdm0//use_tempaddr”. Disable ipv6 for broadband connection helped but it is not the right bugfix. Problem is that network interface for wwan card is registered as wwp0s20f0u2i12 – and exists file /proc/sys/net/ipv6/conf/wwp0s20f0u2i12/use_tempaddr. On the other hand network manager sees device (according to “nmcli device”) cdc-wdm0. Disabling consistent network device naming did not help – wwan interface had name wwan0 after that. HW: Dell Latitude e5570, WWAN – MDM,WRLES,DW5811E,E7,4G,HF. OS: Ubuntu 16.04.2 64bit, Kernel 4.4.0-64-generic

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: network-manager 1.2.2-0ubuntu0.16.04.3
ProcVersionSignature: Ubuntu 4.4.0-65.86-generic 4.4.49
Uname: Linux 4.4.0-65-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.5
Architecture: amd64
CurrentDesktop: Unity
Date: Sun Mar 5 10:59:33 2017
IfupdownConfig:
 # interfaces(5) file used by ifup(8) and ifdown(8)
 auto lo
 iface lo inet loopback
InstallationDate: Installed on 2016-10-26 (130 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
IpRoute:
 default via 100.85.58.157 dev wwp0s20f0u2i12 proto static metric 700
 100.85.58.152/29 dev wwp0s20f0u2i12 proto kernel scope link src 100.85.58.156 metric 700
 169.254.0.0/16 dev wwp0s20f0u2i12 scope link metric 1000
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.NetworkManager.conf.d.default-wifi-powersave-on.conf:
 [connection]
 wifi.powersave = 0
mtime.conffile..etc.NetworkManager.conf.d.default-wifi-powersave-on.conf: 2016-11-24T19:51:44.546944
nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH CONNECTION CON-UUID CON-PATH
 cdc-wdm0 gsm connected /org/freedesktop/NetworkManager/Devices/3 T-Mobile Default e45dd5e2-7424-4403-adae-4defe6c707b7 /org/freedesktop/NetworkManager/ActiveConnection/3
 wlp2s0 wifi disconnected /org/freedesktop/NetworkManager/Devices/1 -- -- --
 enp0s31f6 ethernet unavailable /org/freedesktop/NetworkManager/Devices/2 -- -- --
 lo loopback unmanaged /org/freedesktop/NetworkManager/Devices/0 -- -- --
nmcli-nm:
 RUNNING VERSION STATE STARTUP CONNECTIVITY NETWORKING WIFI-HW WIFI WWAN-HW WWAN
 running 1.2.2 connected started full enabled enabled enabled enabled enabled