Steam download speed drops off a cliff and then stops

The basic problem: When updating a game through Steam, I get an initial spike of network activity, then the download stops.

As displayed by Steam, the speed tapers off:

When looking at the actual network traffic, it spikes once, and then dies entirely:

Some notes here:

• Once the download is down to 0, it stays at 0. Pausing and unpausing the download has no effect. To restart the download, I need to restart Steam.
• Actual data is apparently received for that second, so it is not a case of total blockage. The next time I start Steam, the few MB of data I downloaded are still there. (In theory, I suppose I could get the 1GB download by restarting about 200 times...)

Now, the interesting parts: I can get a less unstable download by placing a severe throttle on the bandwidth.This way I can get a few hundred MB of data rather than about five MB. Nevertheless, it still eventually chokes.

I start the Steam client from a console. The output is rather verbose, but here's an example:

Running Steam on ubuntu 15.04 64-bit
STEAM_RUNTIME has been set by the user to: /home/ernir/.local/share/Steam/ubuntu12_32/steam-runtime
ExecCommandLine: "/home/ernir/.steam/root/ubuntu12_32/steam steam://open/driverhelperready"
ExecSteamURL: "steam://open/driverhelperready"
CAPIJobRequestUserStats - Server response failed 2
ExecSteamURL: "steam://open/downloads"
Generating new string page texture 127: 128x256, total string texture memory is 5,28 MB
Installing breakpad exception handler for appid(steam)/version(1437790054)
Installing breakpad exception handler for appid(steam)/version(1437790054)
Installing breakpad exception handler for appid(steam)/version(1437790054)
Installing breakpad exception handler for appid(steam)/version(1437790054)
Generating new string page texture 128: 128x256, total string texture memory is 5,41 MB
process 4301: arguments to dbus_connection_ref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2656.
This is normally a bug in some application using the D-Bus library.
process 4301: arguments to dbus_connection_unref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2794.
This is normally a bug in some application using the D-Bus library.
process 4301: arguments to dbus_connection_unref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2794.
This is normally a bug in some application using the D-Bus library.
process 4301: arguments to dbus_connection_ref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2656.
This is normally a bug in some application using the D-Bus library.
process 4301: arguments to dbus_connection_unref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2794.
This is normally a bug in some application using the D-Bus library.
process 4301: arguments to dbus_connection_unref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2794.
This is normally a bug in some application using the D-Bus library.
process 4301: arguments to dbus_connection_unref() were incorrect, assertion "connection->generation == _dbus_current_generation" failed in file ../../dbus/dbus-connection.c line 2794.
This is normally a bug in some application using the D-Bus library.
Generating new string page texture 129: 24x256, total string texture memory is 5,44 MB
Generating new string page texture 130: 256x256, total string texture memory is 5,70 MB
Generating new string page texture 132: 48x256, total string texture memory is 5,75 MB

The CAPIJobRequestUserStats - Server response failed 2 line is the only one that looks promising, but searching for it hasn't gotten me anywhere.

Additional information:

• Steam works perfectly on the Windows partition of the same machine.
• The DNS troubles some have mentioned don't seem to be the issue - or at least, installing and restarting dnsmasq didn't do anything.

I am running Kubuntu 15.04 now, the problem was identical under Kubuntu 14.04 and 14.10. System information (as reported by Steam):

Processor Information: Vendor: GenuineIntel CPU Family: 0x6 CPU Model: 0x3a CPU Stepping: 0x9 CPU Type: 0x0 Speed: 3800 Mhz 4 logical processors 4 physical processors HyperThreading: Unsupported FCMOV: Supported SSE2: Supported SSE3: Supported SSSE3: Supported SSE4a: Unsupported SSE41: Supported SSE42: Supported
Network Information: Network Speed:
Operating System Version: Ubuntu 15.04 (64 bit) Kernel Name: Linux Kernel Version: 3.19.0-25-generic X Server Vendor: The X.Org Foundation X Server Release: 11701000 X Window Manager: KWin Steam Runtime Version: steam-runtime-release_2015-06-12
Video Card: Driver: NVIDIA Corporation GeForce GTX 650 Ti/PCIe/SSE2 Driver Version: 4.5.0 NVIDIA 346.59 OpenGL Version: 4.5 Desktop Color Depth: 24 bits per pixel Monitor Refresh Rate: 59 Hz VendorID: 0x10de DeviceID: 0x11c6 Number of Monitors: 2 Number of Logical Video Cards: 1 Primary Display Resolution: 1680 x 1050 Desktop Resolution: 3360 x 1050 Primary Display Size: 18,07" x 11,65" (21,50" diag) 45,9cm x 29,6cm (54,6cm diag) Primary Bus: PCI Express 16x Primary VRAM: 1024 MB Supported MSAA Modes: 2x 4x 8x 16x
Sound card: Audio device: Realtek ALC887-VD
Memory: RAM: 16001 Mb
Miscellaneous: UI Language: English LANG: is_IS.UTF-8 Microphone: Not set Total Hard Disk Space Available: 104234 Mb Largest Free Hard Disk Block: 11192 Mb

Any and all insight is appreciated at this point!

1 Answer

Turns out it was a problem solved by dnsmasq after all.

I can't tell you why it didn't cut it earlier, but on a fresh Ubuntu 15.10 install, I went through the following steps:

First, installing some libraries:

sudo apt-get install libcurl3 libcurl3-gnutls libcurl4-openssl-dev

and then installing Steam. The speed displayed the same characteristics (initial spike, then nothing, as before). However, this time installing dnsmasq and restarting the service did the trick.

sudo apt-get install dnsmasq
sudo service dnsmasq restart

I consider the issue solved, although I would have preferred a solution that didn't involve a full OS reinstall.