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[GUIDE] Troubleshooting wifi issues

Discussion in 'ASUS Wireless' started by RMerlin, Sep 15, 2013.

  1. RMerlin

    RMerlin Super Moderator

    Joined:
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    Canada
    Since the same questions about wireless issues come all the time, with people skipping on some very basic troubleshooting steps, here is a list of things to look for when troubleshooting wireless performance.

    First important thing to keep in mind: wireless is a two-way thing. When troubleshooting, both the router AND the client device must be looked at. Even if "it worked before", that does not mean that the client (be it a laptop, mobile device or other) must be overlooked.

    The first thing to try is to reboot both devices. Sometimes it's all it takes, especially if the router had been running for weeks, or the computer had gone through a couple of sleep/wake cycles since its last reboot.


    If you have wireless AND wired performance issues related to your Internet:

    Make sure that the cable between the modem and the router is rated Cat5e, Cat6 or higher. Older cables will not be reliable with this router since it has gigabit ports.

    Try powering down your modem for 5-10 minutes, then turn it back on. This is especially important with cablemodems.


    If you have only wireless issues:

    General tips (applies to both 2.4 GHz and 5 GHz)

    • Make sure your computer's wireless driver is up-to-date. Check with the manufacturer's website, as Windows Update does not always carry the latest version (in fact, it rarely does). I've personally seen old Atheros drivers that would refuse to connect to any modern router, but worked fine with some older routers.
    • Use a tool such as InSSIDer (Windows) or Wifi Analyzer (Android) to determine which channel is the least busy, then set your router to that channel. Keep in mind that a 2.4 GHz wifi channel will interfere with both neighbouring channels. So if you set it to channel 3, it can be affected by anything also using channel 2 and 4. If your neighbour is on channel 1, then he will also interfere with channel 2. That's why it's usually best to stick with channel 1, 6 or 11, as anything between these will most likely interfere with two other used channels.
    • Try deleting the wireless profile from your device, and reconnecting as if it was a new connection. The device tend to save more technical details than just the SSID and encryption, so sometimes that information can be out of sync with what the router is using.
    • If you had just upgraded the router firmware, try resetting your router back to factory defaults, and reconfigure it manually. Do NOT load a backup of your saved settings, as this will make the whole procedure pointless - you will just end up reloading the exact same incorrect settings you want to get rid of.
    • Router (and antennas) positionning can be important. Picture an imaginary direct line of sight between the router and the client device, and observe what obstacles it has to go through. Each obstacle can affect the radio signal.
    • Going through a wall at a 45 degrees angle will also be worse than at a 90 degrees angle, as it means more surface for the signal to travel through.
    • Increasing the output power rarely helps, unless you were also able to increase the output power of your client devices. If you really need better coverage, upgrade your antennas. And actually cranking the output power too high can cause more issues than anything if you reach a point where the signal gets distorted by the emitter.
    • A 300 Mbps link does not translate in 300 Mbps speed. That's the link speed itself. After that, you have to take into account the encryption, other devices sharing the same channel, retransmission of lost/corrupted packets, etc... Anything around half the link speed is considered good.
    • The link speed can also vary based on power management. It's not unusual for the link speed to drop to a lower value, then rise back up as you are actively transferring data. If evaluating performance, do not look at the link speed alone - do an actual transfer and measure the throughput. Timed file copy or an online speed test with a known good test server are good ways to do so.
    • Sometimes, some wireless adapters just won't like your router. That can happen with older laptop wireless interfaces, or some specific vendors. If it's practical, consider possibly using a different wireless adapter (USB-based, for example). A 300 Mbps adapter is fairly inexpensive these days - cheaper than switching to a different router (for example, switching to a Ralink-based router instead of a Broadcom-based one).

    Issues specific to 2.4 GHz:

    The 2.4 GHz band is VERY crowded. You can get interference from a wide variety of devices:
    • Microwave ovens
    • Baby monitors
    • Old cordless phones
    • Bluetooth devices
    • All your neighbour's routers

    Due to this, you should set channel width to 20 MHz on that band. A 40 MHz connection would require you to overlap no less than 5 channels. Highly unlikely you will get a reliable 40 MHz connection in any urban area with so many channels overlapping. Yes, it will cut your maximum performance in half, but if you want a STABLE connection on the 2.4 GHz band, there is little you can do about this. Otherwise, the 5 GHz band is your only solution.


    Issues specific to 5 GHz:

    • Not every device supports the 5 GHz band. Make sure yours does if you cannot see the 5 GHz SSID at all.
    • The 5 GHz band has a shorter range due to its higher frequency. It also means you are less likely to have interference from your neighbours since their own 5 GHz won't reach as far either, so it's both a curse and a blessing.
    • Common misconception: people expect higher speeds from 5 GHz. That is not the case. The higher number does not mean higher speed, it only means the router is using a different radio frequency. The reason to use the 5 GHz band is not to get more speed, it's to have less interference (which CAN translate in performance improvement over your 2.4 GHz connection, mind you, but not for the reason you might think).
    • On a similar note: simultaneous dual-band means that the router can use both bands at the same time. That does not mean that your computer does - it doesn't.
    • The 5 GHz band is usually split in low numbered channels, and high numbered channels. Some devices work best with one or the other, so try out channels from both areas to see what works best for you.
    • MAC users: some Macs have issues with the 5 GHz band (and sometimes the 2.4 Ghz band too) and Asus routers. The solution usually requires you to connect to your router over SSH or Telnet, and issue the following commands:

      Code:
      nvram set wl0_reg_mode=h
      nvram set wl1_reg_mode=h
      nvram commit
      reboot
      


    Asus-specific issues

    The RT-N66U went through a lot of up and downs in terms of wireless stability. At the time this guide is being written (September 15th 2013), the latest firmware version (3.0.0.4.374.720) should resolves most of
    the connectivity issues. Make sure you do upgrade if you are using an older firmware version, and that you follow the instructions from either this guide or Asus's own changelog. Don't skip on that line that says "revert back to factory default and erase your wireless profile". It's not just meant to make you waste 30 mins of reconfiguring, it's meant to save you fromspending an entire EVENING of troubleshooting, which will often end up in you taking that 30 mins of reconfiguration to resolve the issues.


    Final advice: just because "it worked fine with that other router" does not mean that it's the new router's fault. Wireless technology is very complex, and relies on a bunch of manufacturers interoperating together. If you really want a 100% reliable, sure-to-work technology, stick to Ethernet. In my personal opinion, wireless should be considered as an alternative to Ethernet where it's not practical to run cables, not the other way around.
     
    Quoc Huynh, Rolo, usamario and 10 others like this.
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  3. RedneckBob

    RedneckBob New Around Here

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    Location:
    Austin, Tejas
    Payroll

    Asus should cut you a big fat check. Monthly.
     
    ScottNY, MarcusVR, A Purohit and 3 others like this.
  4. PrivateJoker

    PrivateJoker Very Senior Member

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    And probably small skinny checks from those who enjoy your great work and appreciate you making our equipment better and answering a mind boggling amount of questions on here daily! At least the chances of some small skinny paypals have a better likelihood of coming to fruition. ;)

    http://www.lostrealm.ca/tower/node/80

    Wow, I dunno if this is an ios 7 thing but clicking on PayPal "donate" buttons actually works now on mobile. I'm gonna beta test it right now. :)
     
    albe52 likes this.
  5. RedneckBob

    RedneckBob New Around Here

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    Sent a donation via Pay Pal on Aug 25th.

    Still irritated at Asus for releasing such a dysfunctional router. They need to be sued.
     
  6. PrivateJoker

    PrivateJoker Very Senior Member

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    My too hot to touch class action suit against "big router" has been well underway for several years now. ;)
     
  7. ressac

    ressac Occasional Visitor

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    please mention that stationary elliptical bicycles (at leaste with magnetic resistance) create interference too
     
  8. System Error Message

    System Error Message Part of the Furniture

    Joined:
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    high temperatures can reduce throughput and even cause the device to hang or even spoil the device. As an example I have seen many engenius outdoor routers actually fail because of the extreme conditions (lots of heat, sun and humidity), exposed to really heavy rains and lightning despite being sold as an outdoor unit in a tropical country. Just the heat, sun and humidity is enough to kill the unit. So far ubiquiti does a lot better in that area while being 10x cheaper.

    So add heat to your diagnosis too such as if placing the router in a cooler area or with active cooling helps.

    add firmware to the list too.

    add consideration for rooms that have metal frames that in some way prevents electromagnetic waves of certain frequencies to pass through.
     
  9. srinivasvaradaraj

    srinivasvaradaraj Regular Contributor

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    Location:
    Beaumont, TX, USA
    I would like to add one more thing to the list of possible interference (STA side) :
    USB 3.0 attached devices.
     
  10. cosmoxl

    cosmoxl Senior Member

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    I've found that for 5ghz the setting "enable WMM no acknowledgement", only seen in the professional settings GUI when in N/AC mode, has a profound affect on apple devices. With this setting enabled, my apple devices don't go into low power mode and stay connected. They completely disconnect. Worse yet, this setting, while only visible in N/AC mode, affects all modes (e.g. auto, N only). This is with AC68 with merlin 378.54_1.
     
  11. topet2k12001

    topet2k12001 New Around Here

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    New owner of an ASUS RT-N66U here (less than a month). Just wanted to share. :)

    I had initial issues as this is the first time I have owned a dual-band router, plus my neighbors (I live in a compound) seem to have recently acquired wireless routers too. I have had issues similar to this thread and this thread.

    I usually leave my router's firmware at default settings (be it stock or DD-WRT, and this time around, ASUSWRT-Merlin). Apparently with dual-band routers you need to "do your homework". :)

    So, learning from this thread/guide, I set my 2.4 GHz band to:

    1. Channel Bandwidth: 20 MHz
    2. Wireless Mode: "Legacy" or "Auto" - initially I set it at "Legacy" since I only have two (2) wireless N devices (both cellphones)
    3. Control Channel: I learned how to use InSSIDer. Pretty nifty. It clearly pictures out which "channels" my neighbors routers are on, so as for me to know which "channel" to set on my router. Plus of course, the troubleshooting guide in this thread helped me understand "overlaps" better. Back then I just left the "channel" setting at "Auto" on previous routers and I have observed (with InSSIDer) that routers behave in a way that, if there is an "overlap", it will automatically switch channels. In my case, I observed that my neighbor's routers don't use Channel 1, so I set mine on Channel 1. :)

    ...and then I set my 5 GHz band to:

    1. Wireless Mode: N only (I don't have wireless A or 802.11 A devices anyway)
    2. Channel Bandwitdh: 40 MHz. I'm not sure if I should just leave it at the default 20/40, or just 20 MHz, since again I only have two (2) wireless N devices (cellphones); all the rest are "G".
    3. Control Channel: I left it at "Auto" since as per the tutorial (and some reading over the Internet), there's not a lot of devices currently supporting "Wireless N" so there'll be a small chance of "overlap" with my neighbor's routers, if any.

    So far so good! I was at the brink of having my router replaced, or call my ISP to complain (but I was already able to isolate my ISP since directly connecting a PC/laptop physically to the modem showed no issues - I get my subscribed speed).

    Just wanted to share this experience so that others may benefit, and hopefully posting in this thread will make it easier to find (I had to do my own research through the Internet).

    More power to you!
     
    heysoundude and Princz like this.
  12. Surenthiran

    Surenthiran New Around Here

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    Dec 3, 2015
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    hi. need some advice on making changes to my home network/wifi. my internet modem and router from the ISP is setup in my TV room on the ground floor in my house. this has made it difficult to near impossible to get any wifi reception on the first floor and bedrooms. the good part in all these is that i had run cat5e network cables behind my walls extending from the TV room to the living room on the ground floor, family area and master bedroom on the first floor during renovation works. i am thinking of adding access points with extra routers to allow better wifi reception throughout the house. i also plan to change the existing router given by my ISP. pls advise on which asus router would be suitable in which parts of the house (ie: main router and access point routers)? thanks.
     
  13. heysoundude

    heysoundude Senior Member

    Joined:
    Sep 20, 2016
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    for those with range/coverage issues, you don't need to play with power, you need better antennae:
    http://ham-radio.com/k6sti/wifiyagi.htm
    This was designed to function best in the 2.4GHz band, but may work in the 5GHz band as well
     
  14. dlandiss

    dlandiss Senior Member

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    Location:
    St. Louis, MO
    Do keep in mind that yagis and similar multi-element antennas trade range for beamwidth. That is, they perform quite well in one direction at the expense of other directions.
     
    heysoundude likes this.
  15. heysoundude

    heysoundude Senior Member

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    quite right. using this would make your router (or antennae, if they're remote to the router) locations rather important.
     
  16. heysoundude

    heysoundude Senior Member

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    @RMerlin - the nvram commands from post #1, are they still germane to the latest version, and are they a one-time thing or do they need to be re-entered at each reboot?
     
  17. RMerlin

    RMerlin Super Moderator

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    The 802.11h ones? No, they are now overridden by the closed source components of the firmware.

    That post probably needs revising, I just lack the time (and the motivation) to do so, sorry. I might eventually just un-stick it.
     
  18. Boudreaux

    Boudreaux New Around Here

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  19. Boudreaux

    Boudreaux New Around Here

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    I want to thank those responsible for the post above. I had a Netgear Nighthawk X6 (purchased on Nov15th '17). It worked "very well" until Christmas when everything went very bad. Today I purchased an ASUS RT-AC1900, Connected the unit as required and got only partial wifi connections on some devices and not others. (very strange). I came here about two hours ago, joined, and the very first post I read was this one (about turning "everything" off).

    Well. it worked so very well ...... "THANK YOU VERY MUCH" ......
     
    Last edited: Jan 6, 2018
  20. RMerlin

    RMerlin Super Moderator

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    Canada
    Quick addendum, as I lack the time to maintain the original post:

    In newer routers, if you experience wireless stability issues then it's recommended that you disable the following options:

    • MU-MIMO (some hardware revisions have non-functional/unreliable implementations)
    • Airtime Fairness (causes connectivity issues for various devices, including wireless printers)
    • Universal Beamforming (non-standard, might cause compatibility issues with some clients)
     
    jspuds likes this.
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