Macbook Air network unreliable under Xenial

[Jeff Lane ]

This seems to be a regression from Wily. I previously had Wily installed on this Macbook Air and noticed no issues with network connectivity.

Yesterday I upgraded to Xenial and networking has been unreliable ever since. It seems to be OK after booting, but after a while of use (maybe an hour? maybe less) I start to see a lot of packets dropped and very high RTT per ping.

At first I thought this may have been an issue with my ISP, as I was seeing THIS while pinging 8.8.8.8 from my Xenial install:

 64 bytes from 8.8.8.8: icmp_seq=116 ttl=40 time=28.5 ms
64 bytes from 8.8.8.8: icmp_seq=117 ttl=40 time=27.8 ms
64 bytes from 8.8.8.8: icmp_seq=122 ttl=40 time=49879 ms
64 bytes from 8.8.8.8: icmp_seq=123 ttl=40 time=49096 ms
64 bytes from 8.8.8.8: icmp_seq=124 ttl=40 time=48228 ms

But I pinged using a network tools app on iOS connected to the same WiFI network (using Cable internet as the outbound connection) and pings were very steady in the 30ms range with no dropped packets.

Needless to say, this makes working VERY difficult, as I am unable to reliably do hangouts, download files, work on GoogleDocs, or maintain SSH connections or VPN connections because of the unreliable network.

So I rebooted and ran several ping tests on OSX, and the results are as follows:

--- 8.8.8.8 ping statistics ---
100 packets transmitted, 100 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 21.692/30.785/91.193/12.906 ms

--- 8.8.8.8 ping statistics ---
100 packets transmitted, 100 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 21.726/28.498/58.639/7.604 ms

Then on Xenial after rebooting:
bladernr@Rogue1:~$ uptime
 15:06:12 up 42 min, 2 users, load average: 0.17, 0.18, 0.21

--- 8.8.8.8 ping statistics ---
100 packets transmitted, 26 received, 74% packet loss, time 99612ms
rtt min/avg/max/mdev = 22.456/42.526/168.247/39.368 ms

--- 8.8.8.8 ping statistics ---
100 packets transmitted, 77 received, 23% packet loss, time 99275ms
rtt min/avg/max/mdev = 23.043/36.687/195.534/28.956 ms

--- 8.8.8.8 ping statistics ---
100 packets transmitted, 43 received, +6 errors, 57% packet loss, time 99525ms
rtt min/avg/max/mdev = 23.866/339.391/4078.260/859.057 ms, pipe 5

And this is from my phone, run around the same time the pings were run from Xenial showing such issues with traffic:

Results Summary
Average RTT 41.97 ms
Min/Max RTT 24.05/199.18 ms
STD Deviation 26.37 ms
Packets (Rvcd/Sent) 104/104 (100%)

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-4.4.0-21-generic 4.4.0-21.37
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: bladernr 1614 F.... pulseaudio
 /dev/snd/controlC1: bladernr 1614 F.... pulseaudio
CurrentDesktop: Unity
Date: Thu Apr 28 14:58:17 2016
HibernationDevice: RESUME=UUID=1ec334c0-b29f-454a-9668-0e6f5cc2d152
InstallationDate: Installed on 2015-10-21 (189 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151020)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 003: ID 05ac:0290 Apple, Inc.
 Bus 001 Device 006: ID 05ac:828f Apple, Inc.
 Bus 001 Device 002: ID 0a5c:4500 Broadcom Corp. BCM2046B1 USB 2.0 Hub (part of BCM2046 Bluetooth)
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Apple Inc. MacBookAir6,1
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.4.0-21-generic.efi.signed root=UUID=36666d44-163a-4386-9871-83e8515efd90 ro quiet splash vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-4.4.0-21-generic N/A
 linux-backports-modules-4.4.0-21-generic N/A
 linux-firmware 1.157
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/08/2015
dmi.bios.vendor: Apple Inc.
dmi.bios.version: MBA61.88Z.0099.B20.1509081314
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-35C1E88140C3E6CF
dmi.board.vendor: Apple Inc.
dmi.board.version: MacBookAir6,1
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-35C1E88140C3E6CF
dmi.modalias: dmi:bvnAppleInc.:bvrMBA61.88Z.0099.B20.1509081314:bd09/08/2015:svnAppleInc.:pnMacBookAir6,1:pvr1.0:rvnAppleInc.:rnMac-35C1E88140C3E6CF:rvrMacBookAir6,1:cvnAppleInc.:ct10:cvrMac-35C1E88140C3E6CF:
dmi.product.name: MacBookAir6,1
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.

[Brad Figg (brad-figg)]

This change was made by a bot.

[Joseph Salisbury (jsalisbury)]

Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.6 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.

[0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.6-rc6-wily/