Wifi deactivated when on battery

[andreaconsole]

When i unplug the power cord, after a while, it happens that the wifi stops working (it says that my connection is deactivated and I don't see any available connection anymore in the network manager, as if the wifi card weren't working).
There is no error alert and, looking at the Network Manager from its tray icon, everything seems ok (apart that I see no networks).
The only solution I found till now is to restart the computer, since re-plugging power cord doesn't help.
Since it's related with power, I supposed that it was something related to powersave mode, but iwconfig says that there is no powersave mode active. I also tried to add the "wireless" file as suggested here (but it should work only if there is a powersave problem, indeed): https://itechscotland.wordpress.com/...ent-in-ubuntu/
I'm working with kubuntu 14.04 - fully updated - on a laptop ASUS X5DIJ, but I had different versions of kubuntu since 10.04 on this computer without experiencing such problem.
Have you got any suggestion?

[TWPonKubuntu]

Check your power management setting under System Settings

[andreaconsole]

Thank you for your answer, TWPonKubuntu, but as far as I can see there are no settings for wifi...

[TWPonKubuntu]

It might be a BIOS configuration for power conservation.
I'm on a desktop now, so I cannot test this.

[oshunluvr]

Not generally a laptop user here but you should install the power utilities then you will have more control. Also look at the output of "rfkill" when it's on and again when it goes off.

Odd thing is it seems backward. My old Dell would turn off the ethernet port when on battery but leave wifi on.

[andreaconsole]

hi friends,
some update:
I found that the problem, even if it occurs only when on batteries, is quite random.
I think I'm in this case, because I have the same output from dmesg:
https://bbs.archlinux.org/viewtopic.php?id=137643

I think that there are some issues with my wifi card (Qualcomm Atheros AW-NE785 / AW-NE785H 802.11bgn Wireless) and my kernel, so I tried to find if there is a proprietary driver for my hardware, but the "new driver manager" seems useless...

It's annoiyng because since it occurs randomly I can't do tests...

[aria]

Driver issue IMO, just like you suspect. Jokey (driver manager) won't show a proprietary drivers for atheros, as it works with open source. Still, the company could have made available for download, on their site, a new version, not yet included in a kernel. You should visit their site, download and install the driver from that source, even if the same you use now (could have been corrupted, and reinstalling it solves the issue). Or wait for a new kernel, hopefully including a new driver. Meanwhile, I believe you can reactivate the wifi by shutting it of and than on from the dedicated F button (on my acer it is F3). No need to reboot.

Another suggestion. When wifi goes off, type in a terminal the code:

kdesudo kate /var/lib/NetworkManager/NetworkManager.state

You should see:

NetworkingEnabled=true
WirelessEnabled=true
WWANEnabled=true
WimaxEnabled=true

If a value is false, change it to true, save and exit. Should work now. But if a driver issue, all values will show true, and wifi still won't work. Reinstalling the driver should do it. I broke the wifi driver recently doing something wrong with the hdmi. Reinstalled the driver and all went fine.

[aria]

PS: Also, try to reset the router. Do not reset from the button on the back, should have an assisted re-setting/installing procedure, having already all data memorized in, so all you have to do is "next", "next"... "finish". I had to do this when moved from 12.04 to 14.04, while keeping the same computer name and username for the new system. The router disconnected me after several minutes, because it couldn't manage the system change with keeping the same computer and user names. Procedure took less than 5 min. Did it wired (wifi wasn't reliable until reset). All worked fine after this.

[SteveRiley]

I think I'm in this case, because I have the same output from dmesg:
https://bbs.archlinux.org/viewtopic.php?id=137643

I think that there are some issues with my wifi card (Qualcomm Atheros AW-NE785 / AW-NE785H 802.11bgn Wireless)

The Arch forum post has instructions for disabling hardware encryption on the wifi interface. (Don't worry, encryption still happens, just using the regular CPU.) Did you try that? We've had others here on the forum experience similar problems with Atheros wifi, and the suggested fix has worked.

[andreaconsole]

Hi guys,
thank you for all your answers and for your effort in helping me. As usual, I waited for the problem to show in order to make tests.
Just to sum up, AFAIK,
- the disconnection happens only on batteries, both when I start the pc on batteries and after unplugging the power cord.
- it's not instantaneous, but it happens after few minutes;
- after disconnection, I find this:

>sudo kate /var/lib/NetworkManager/NetworkManager.state
[main]
NetworkingEnabled=true
WirelessEnabled=true
WWANEnabled=true
WimaxEnabled=true
WiMAXEnabled=true

and this:
>dmesg
...
[17029.026512] ath: phy0: Could not stop RX, we could be confusing the DMA engine when we start RX up
[17029.142254] ath: phy0: Chip reset failed
[17029.142259] ath: phy0: Unable to reset channel, reset status -22
[17029.142275] ath: phy0: Unable to set channel
[17029.208806] ath: phy0: Failed to stop TX DMA, queues=0x18f!
[17029.221716] ath: phy0: DMA failed to stop in 10 ms AR_CR=0xffffffff AR_DIAG_SW=0xffffffff DMADBG_7=0xffffffff
[17029.221724] ath: phy0: Could not stop RX, we could be confusing the DMA engine when we start RX up
[17029.337432] ath: phy0: Chip reset failed
[17029.337436] ath: phy0: Unable to reset channel, reset status -22
[17029.337449] ath: phy0: Unable to set channel
[17029.340005] ath: phy0: RX failed to go idle in 10 ms RXSM=0xffffffff
[17029.340005] ath: phy0: DMA failed to stop in 10 ms AR_CR=0xffffffff AR_DIAG_SW=0xffffffff DMADBG_7=0xffffffff
[17031.011366] ath: phy0: Failed to wakeup in 500us
[17031.018771] ath: phy0: RX failed to go idle in 10 ms RXSM=0xffffffff
[17031.018771] ath: phy0: DMA failed to stop in 10 ms AR_CR=0xffffffff AR_DIAG_SW=0xffffffff DMADBG_7=0xffffffff


- this is my wireless card according the PC:
description: Wireless interface
product: AR9285 Wireless Network Adapter (PCI-Express)
vendor: Qualcomm Atheros
physical id: 0
bus info: pci@0000:02:00.0
logical name: wlan0
version: 01
serial: 1c:4b:d6:a2:d9:7d
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress cap_list ethernet physical wireless
configuration: broadcast=yes driver=ath9k driverversion=3.13.0-45-generic firmware=N/A latency=0 link=no multicast=yes wireless=IEEE 802.11bgn
resources: irq:17 memory:feaf0000-feafffff;
BUT, i opened the PC and indeed it's AR-5B95...

- only a full restart (the hybernation is not sufficient) restores the connection, the other commands don't do anything...

- I can't find any wireless powersave-related settings neither in system configuration nor in BIOS;

- I have the ath9k driver updated for 14.04 and there are no vendor's specific drivers available.

LATEST UPDATES:
I changed the router and made very intensive downloading for a while: I experienced disconnections also with the power cord connected. I'm starting to think that this is a (rare) case of hardware issue!

[andreaconsole]

LAST update, I think...
I did a test I should have done before: boot with windows... the problem is still present. Now I'm quite sure it's a hardware issue. Sorry for having wasted your time :$