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Inconsistent internet speed

742 Views 11 Replies Latest reply: May 3, 2012 3:01 PM by Csound1 RSS
OlivierVeyrac Calculating status...
Currently Being Moderated
Apr 18, 2012 10:46 AM

My internet speed on my Mac suddenly drop to less than 1 Mbps and stays like that for a few hours, then goes back up to 25 Mbps. I have already:

- Checked with my ISP and it is not coming from them + the other computers are running full speed on the same wireless network.

- Checked on this computer in both Mac OS and Windows on Bootcamp - the problem is the same.

- Ran an antivirus (Norton) on the Windows partition (I did not have one for the Mac partition).

- Tryed to run off a different wireless network at a friend and the problem persist.

- I messed around with the DNS - but it was hard to diagnose if it was the problem as the speed was good at that particular time.


Here are my guesses:

- Could it be a problem with the Wireless adapter (I un-installed and re-installed and it did not do anything.

- Could I have a virus on the Mac Partition that would also affect the windows partition? How can I check?


Thanks for the help.

iMac (Flat Panel), Mac OS X (10.6.8)
  • rkaufmann87 Level 8 Level 8 (40,505 points)
    Currently Being Moderated
    Apr 18, 2012 11:04 AM (in response to OlivierVeyrac)

    No viruses as none exist for OS X so you can eliminate that!


    I suspect it's a modem or router issue. Even though the other computers work OK don't assume that isn't the cause. I would recommend by rebooting and if necessary resetting both your modem and router. Also check the router's firmware (you will need it's manual) and see if it's up-to-date.


    If you live in a heavily populated area you may want to download and install iStumbler (check on and let iStumbler run for about 30 minutes. What it's going to do is scan the area for Wi-Fi networks and let you know what channel(s) are being used. Most routers come pre-set to channels 5 or 6 and most people never change the channel. So you may find  you are competing for channels with neighbors. If that is what you find change the channel on the router to one not being used and then test.


    Your DNS settings may also need changing, that is something you can also do however if you are not sure how to do this let's get done with the iStumbler test and channel change before changing any settings.

  • rkaufmann87 Level 8 Level 8 (40,505 points)
    Currently Being Moderated
    Apr 18, 2012 11:54 AM (in response to OlivierVeyrac)

    After you have updated the firmware download and test the channel possiblity using iStumbler that  I mentioned. Try that next and see what comes up.

  • rkaufmann87 Level 8 Level 8 (40,505 points)
    Currently Being Moderated
    Apr 19, 2012 7:18 AM (in response to OlivierVeyrac)

    What channel is your router using?

  • rkaufmann87 Level 8 Level 8 (40,505 points)
    Currently Being Moderated
    Apr 21, 2012 10:24 AM (in response to OlivierVeyrac)

    OK, you have eliminated channel conflict issues. The next thing I'd check is your DNS settings, you probably used the defaults provided by your ISP. Those can create issues such as you're describing. You can change them easily and I'll provide instructions below. Before I do you may want to read up on MacWorld's DNS Troubleshooting article and CNET's DNS Article  to get a better understanding of DNS.


    1. System preferences

    2. Network

    3. Click Advanced

    4. Click DNS tab

    5. Click + sign

    6. Add

    7. Click + sign

    8. Add

    9. Click OK.

    10. Exit System Preferences

  • rkaufmann87 Level 8 Level 8 (40,505 points)
    Currently Being Moderated
    Apr 23, 2012 5:35 PM (in response to OlivierVeyrac)

    I can't say on the Boot Camp side because I don't use it. I'm pretty much an OSX person. First let's see if the DNS setting works on OS X and then if you need or want you can ask on the Boot CAmp forum.

  • Csound1 Level 7 Level 7 (32,270 points)
    Currently Being Moderated
    May 3, 2012 3:01 PM (in response to OlivierVeyrac)

    OlivierVeyrac wrote:


    I tried to use a couple of utilities supposed to find the fastest DNS for me. I used their recommendation - no improvement. I will use your's and let you know. Other question: I am using Windows on Bootcamp. Do I need to go to the mac partition, change the DNS there. or do it on Windows? I noticed that the default DNS are the same in windows and mac (By the way, other computers using the same DNS do not have the same issue.

    Windows (in bootcamp) and OSX are entirely separate, nothing you change in one affects the other, change both. Slso, try hardwiring to the router (as a test).


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