After upgrading 14.04 to 16.04 I couldn't send big emails with attachments, I couldn't use google drive. Sometimes lowering the MTU worked.
I was able to get uploading of large files working again by playing with MTU probing and discovery:
echo 1 > /proc/sys/net/ipv4/tcp_mtu_probing
echo 1024 > /proc/sys/net/ipv4/tcp_base_mss
Basic MTU related issues should be setup by default, perhaps interfaces need to updated during upgrade?
Ubuntu 4.4.0-21.37-generic 4.4.6
Without enabling tcp_mtu_probling I couldn't upload large files over HTTPS and SMTP w/ TLS.
---
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/dsp', '/dev/snd/by-path', '/dev/snd/hwC0D3', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D8p', '/dev/snd/pcmC0D7p', '/dev/snd/pcmC0D3p', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/controlC0', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CurrentDesktop: GNOME-Flashback:Unity
DistroRelease: Ubuntu 16.04
EcryptfsInUse: Yes
InstallationDate: Installed on 2011-12-09 (1599 days ago)
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
MachineType: LENOVO 4294CTO
Package: linux (not installed)
ProcFB: 0 inteldrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-21-generic root=UUID=2e608b01-21da-49d9-a0fa-ff80b90454a8 ro pcie_aspm=force i915.i915_enable_rc6=1 i915.lvds_downclock=1 i915.i915_enable_fbc=1 quiet splash nomdmonddf nomdmonisw nomdmonddf nomdmonisw nomdmonddf nomdmonisw nomdmonddf nomdmonisw vt.handoff=7
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
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
RfKill:
0: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no
Tags: xenial
Uname: Linux 4.4.0-21-generic x86_64
UpgradeStatus: Upgraded to xenial on 2016-04-25 (0 days ago)
UserGroups: adm admin cdrom dialout docker libvirtd lpadmin netdev plugdev sambashare video
_MarkForUpload: True
dmi.bios.date: 10/18/2011
dmi.bios.vendor: LENOVO
dmi.bios.version: 8DET54WW (1.24 )
dmi.board.asset.tag: Not Available
dmi.board.name: 4294CTO
dmi.board.vendor: LENOVO
dmi.board.version: Not Available
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Not Available
dmi.modalias: dmi:bvnLENOVO:bvr8DET54WW(1.24):bd10/18/2011:svnLENOVO:pn4294CTO:pvrThinkPadX220Tablet:rvnLENOVO:rn4294CTO:rvrNotAvailable:cvnLENOVO:ct10:cvrNotAvailable:
dmi.product.name: 4294CTO
dmi.product.version: ThinkPad X220 Tablet
dmi.sys.vendor: LENOVO
This bug is missing log files that will aid in diagnosing the problem. From a terminal window please run:
apport-collect 1574933
and then change the status of the bug to 'Confirmed'.
If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.
This change has been made by an automated script, maintained by the Ubuntu Kernel Team.