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Hello, Unfortunately, I am here today having to ask for some help with wifi performance. Here's the thing; in my university residence, they've removed our wired internet in favour of ...
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  1. #1
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    Conversion from Ethernet to WiFi, help with performance?


    Hello,

    Unfortunately, I am here today having to ask for some help with wifi performance. Here's the thing; in my university residence, they've removed our wired internet in favour of wireless. We used to have ~10MBps down speeds, but now I'm lucky when I get 300KBps down. Over this summer term (May - August), there thankfully is maybe a quarter of the amount of people that typically live in residence (which is ~800); however, their wifi system cannot handle the traffic as it is it seems. Thing is, they just put in the wifi last October, so the system is still new, all these fancy Cisco wifi APs on every floor (at least two per floor).

    Thing is, I have a couple problems now, many of them unsolvable. For one, I no longer have wireless printing as I cannot manually enter wifi settings on my printer, it requires WPS which now I don't have access to. But the main issue is the wifi performance on my desktop. I get disconnected quite often, and a typical trend in my connection is as follows:

    1. Enable my wifi card
    2. Card connects to wifi ap belonging to the residence
    3. Internet speeds are usable...
    4. Internet speeds gradually decrease over time
    5. Either get disconnected from AP or, more common, I have no down speed
    6. Disable wifi card
    7. Go to number 1


    Now I also have an android tablet and phone that, while the internet speeds aren't great, don't have this issue. In my desktop, I've used two wireless cards, both of which have the same issues. One was a Ralink RT61 based card (limited to 802.11b/g) and my current is (according to lspci) an Atheros AR93xx based card, which has 802.11n, dual antenna for 2.4/5GHz support.

    What I've tried is, from within my wifi settings, locked the NIC to a BSSID. The thing is the BSSID addresses are not always in range for some reason, and, making things even so much more of a headache, when scanning the waves with an app on my phone, I've found that from the area around my desktop, there is reception to around 36 individual APs!! I mean the building is 13 floors high, and I'm at one end of the building, and the building may be, say...150m in length? Maybe 200? And there is (as far as I know) only two APs per floor.

    If anyone would like to see a log of the wifi APs in my area, I can also post a text file containing that info. As well, of course, if any other information is needed I'd be happy to provide it.

    In a nutshell, is there anything on my end that I can do to A) increase performance, or at least B) stay connected more reliably?

    Thanks,

    Nathan Ell

    System info:

    Linux Mint 16, kernel 3.11.0-23, system always up-to-date with LM repositories.
    Realtek 8111 (eth), Atheros AR93xx (wlan - D-Link DWA566)

  2. #2
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    Can you connect an external wifi antenna to your laptop?

  3. #3
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    Well, this is a desktop so I know that antennas are going to be a little issue. However, I have tried an external antenna and it doesn't do anything to improve the performance. It does improve the signal level a bit but doesn't help with the issues above.

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    Well i was going to suggest doing
    this.


    freeantennas.com/projects/template/
    i have used a similar one in the past to increase my reception, because the wifi was 3 stories below. It did make the connection more reliable.

    or buy a cord to place the antenna as close as possible to the AP.

    Or look up tx-power. I don't know what it does, and i vaguely remember messing with it, but it has something to do with wifi receptions.

  5. #5
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    Yeah I know my reception isn't outstanding, but it's not that bad either. I've installed the utility wavemon, and it reports that I've usually got a link quality of 30-50 out of 70 so reception levels of 43% to 71%. From what I know, transmit power is mostly just concerning the router. Regarding this, I found this from another forum post elsewhere: when you increase router tx-power, all it does is make it
    kinda like talking through a bullhorn with earplugs in. they hear you, you don't hear them
    . Also, from another post (this time from askubuntu), I found that to increase tx-power on a client side,
    It doesn't help that much. It'll only help if you're pushing the range to the limits
    which I'm not. From what I know, in Canada (my location of residence) the maximum tx-power changes depending on the frequency that the wifi network is sitting at. For example, currently I'm connected to a 5.32GHz frequency AP and I'm reporting a tx-power of 20dBm (which is 100.0 milliwatts), while the legal limit for this frequency is 24dBm (251.2mW).


    In the end, my reception is fair and I feel that I should still have much better performance, rather than my speeds dropping off over time AND the system changing APs so frequently. While writing this post I was monitoring the activity using wavemon and I watched the system disconnect and reconnect to a different AP at least 8 times!

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    I'm kind of out of ideas....
    Are you sure it is not your card that causes the problems? Have you tried this at other places? Tried updating drivers?
    Other than asking to have the AP closer to your room, i have no solution.

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    Well I've moved my desktop a bit to see what I can do but it hasn't seemed to help. I don't believe it's a driver issue because two different cards (one Atheros, one Ralink based) show the exact same behaviour. I cacn look into updating the drivers as I'm just using whatever works stock.

    I don't have any other ideas either. To be frank, I'm at a total loss for what the reasons are. I do also have a personal laptop. My desktop is under my desk, and if I set my laptop right next to my desktop so the antennas would be in roughly the same location, the laptop has just dandy performance.

    I guess that really I can make do with it as it is right now. I'm a computer science student and it could start to become a problem in my later years of my degree. My university has a student linux server that we can access to experience (and save time on) building large applications on a 128-core machine and it'll start to be more important when I have to transfer large files back and forth to do the work. Yeah I could do all my work over SSH on the remote machine but I don't always have internet when I'm working so that doesn't work.

    Anyway I'm getting further than I need to. At the end of the day I'm stumped too, and hope someone could have a different idea. Thanks for your suggestions! I'll check out the drivers too.

  8. #8
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    Good luck with your quest!
    Why do you think the laptop has dandy performance but the desktop not?

  9. #9
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    Thanks Well on my laptop I don't have the issues described above. My wifi connection is stable and the speeds are consistent. This is in contrast to my desktop, where I get disconnected often, and in general the internet down speeds slow over time, to the point where I have to disconnect from the current AP and reconnect. On the laptop, as well as my smartphone and tablet, I don't get disconnected and my speeds stay relatively consistent.

  10. #10
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    If the laptop and phone work consistently and the desktop does not - the problem is with the desktop not the WiFi system. I would continue to look at a driver/configuration issue with the desktop. Buntu based distros have had problems like this for a long time with certain WiFi chipsets. As an example, Google "rtl8192ce connection problems" and you'll find a ton of info (I have this on one of my laptops and it was having issues).. Find out which kernel WiFi driver the card is using and then start searching.

    One thing I have done generally is disable IPV6 on all my wireless connections and I have more stability. I have also had strange performance with 802.11n where 802.11g is rock solid. WiFi is a really difficult area to troubleshoot as there are a lot of things happening with hardware, software, drivers, and communication standards...

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