Re: [BLUG] Xfinity, Ubuntu woes

At 5:07pm -0400 Sat, 09 Aug 2014, Lawrence Bottorff wrote:
> I'm on U14.04 on my Thinkpad X201. I could not get Wifi to work at
> all initially. Then a Xfinity support person "changed something" and
> it . . . sort of worked.

In context of the second sentence, it's not clear to me whether you are
talking about the Xfinity hardware, or your laptop. Did the Xfinity
support personality help you with Linux on your laptop? If so (and I
gather from the other messages in this thread that they did), then I'm
impressed, as I'm not aware of too many Linux support options for the
desktop (okay, laptop) user.

I'm also curious: you say they changed "something". How did they do
this? Did you give them root access to your machine?

> That means it worked after fiddling with enable, disable, (I'm on
> Gnome classic). Actually, I don't know what I would do, but
> eventually it would work.

For debugging purposes, it's important to describe what you mean by
"wouldn't work". Does the network just stop responding? For example,
are you in the middle of downloading a web page which stops halfway
through, and then you note that you can't do anything (open any other
website in another tab, ping a google.com, etc.)? Does the
NetworkManager applet animate as if it's unable to connect to a network?

In a later message, you pasted some lines from the syslog. I think some
bits are missing from each session, which may be important for tracking
down the issue. Nevertheless, I do note one difference:

Bad session: NetworkManager[1525]: <info> Policy set
'HOME-2D4F-2.4' (wlan2) as default for IPv4 routing and DNS.

Good session: NetworkManager[1525]: <info> Policy set
'HOME-2D4F-5' (wlan2) as default for IPv4 routing and DNS.

Given just this difference, 2.4 vs 5, I wonder if there is a mismatch in
either the Xfinity implementation of 802.11n ("Wireless N"), or -- more
likely -- is the wireless N driver incomplete on your X201? In other
words, given 802.11n, it is _not_ strange that it wants to use both
frequencies (recall that 802.11n is a MIMO technology), but I wonder if
the implementation is buggy. Specifically, I know that Intel wireless
Linux drivers had, at one point, some issues with 802.11n. Do they still?

> Then I'd put it in suspend, come back . . . and it wouldn't work.
> Repeat fiddling, rebooting, etc., then it would work. Any ideas what
> I'm having probs with?

Notwithstanding my above question, this general behavior echoes
experiences I've had with some wireless firmware and kernel modules. In
the end, my solution was to remove the module, and reinsert it. Since
your lshw output suggests you use iwlwifi as your wireless driver,
here's the relevant action from the command line:

$ sudo modprobe -r iwlwifi
$ sudo modprobe iwlwifi

This is the moral equivalent of rebooting, but at the driver level. At
this point, if it doesn't "just work", you should be able to restart
NetworkManager (sudo service networkmanager restart). That simple trick
has fixed 90% of my wireless "stopped working randomly or post-suspend"
issues on Linux.

Cheers,

Kevin
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