My iMac is having increasing trouble connecting to the Internet

Discussion in 'iMac' started by Galumph, Aug 21, 2015.

  1. Galumph macrumors newbie

    Joined:
    Aug 21, 2015
    #1
    My iMac (Yosemite 10.10.5) is having increasing trouble connecting to the Internet. Everything has been AOK for over a year with this same configuration, then it started out just taking a minute to connect whenever I opened mail or message or a browser. Now it will not connect except periodically.

    This is a wired connection so it’s not a WiFi issue. Neither is it a DNS issue. The pipe is not to blame because I have hooked up numerous laptops to it and all is functioning well (3 up/30 down, just like it’s supposed to be). When it’s not connecting my network display in system prefs states “cable unplugged.” I have tried fiddling with the ethernet cable at the connector in the rear of the display to ascertain whether that is the cause, but I cannot get it to malfunction when I am connected.

    The hard drive has ample room (573 gigs available), the activity monitor looks good (over 90% idle at the moment) and, anyway, I keep few programs open simultaneously and always store my big files on external hard drives. I run disc utility religiously so I don’t think it’s a file corruption. I’m wondering if it might be a hardware issue internally that is randomly toggling my online status off and on. The only other thing I can imagine is that there’s some sort of invasive file stuck in there somewhere that’s wreaking progressive havoc.

    I am stumped. I would be grateful for any suggestions.
     
  2. matreya macrumors 65816

    matreya

    Joined:
    Nov 14, 2009
    #2
    Have you tried a different ethernet port on the modem/router? Have you tried Wifi?
     
  3. InAustralia macrumors 6502

    InAustralia

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    Oct 7, 2013
    Location:
    Sydney, Australia
    #3
    As suggested above, try using another ethernet port or WiFi (or even swapping out the ethernet cable used). This is really just a trouble shooting step to see if it's a physical issue or a software issue.

    I was experiencing a similar issue where my wired iMac would take a long time to connect to the internet too. I tried lots of trouble shooting steps and eventually tracked down my problem to a corrupted system preference file.

    If the problem still exists on WiFi or after using a different ethernet cable, then you could try this.

    Go to iMac/Library/Preferences/SystemConfiguration

    Then take a copy of the files below (as a backup) and place them somewhere (like your desktop so you can restore them if the fix does not work). Then delete the files from your mac, empty the trash and reboot.

    com.apple.airport.preferences.plist
    com.apple.network.identification.plist
    NetworkInterfaces.plist
    preferences.plist

    The reboot process will rebuild your system preference files, and if it was a corrupt preference file, the problem should be fixed.

    Hope this helps.
     
  4. Galumph thread starter macrumors newbie

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    Aug 21, 2015
    #4
     
  5. Galumph thread starter macrumors newbie

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    Aug 21, 2015
    #5
    Yes, I changed ports numerous times just for the heck of it, but since laptops on the same cable have good connectivity the particular router port seems irrelevant. I have not tried WiFi as my iMac is in an outbuilding on the property & too far removed for effective WiFi, thus the use of underground-grade ethernet cable.
     
  6. filmak macrumors 6502a

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    Jun 21, 2012
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    between earth and heaven
    #6
    Try to setup a new location in the network preference pane, also make sure that ethernet is selected as the first service to use.
     
  7. filmak macrumors 6502a

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    Jun 21, 2012
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    between earth and heaven
    #7
    Also check the ethernet receptacle with a flash light, for any damages...
    And a PRAM reset...
     
  8. Fishrrman macrumors G3

    Joined:
    Feb 20, 2009
    #8
    OP wrote:
    "I have not tried WiFi as my iMac is in an outbuilding on the property & too far removed for effective WiFi, thus the use of underground-grade ethernet cable."

    How far from the router is the Mac?
    How long is the underground cable?
    Is the underground cable category 5 or category 6?
    Have you tried REPLACING the underground cable?

    Have you tried moving the Mac into the main building, next to the router, connecting via a short Ethernet cable?
    How is the iMac if you try this (for experimental purposes only)?

    I sense that you have a connection problem (as in "physical" connection)...
     
  9. Galumph thread starter macrumors newbie

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    Aug 21, 2015
    #9
     
  10. Galumph thread starter macrumors newbie

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    Aug 21, 2015
    #10
    Distance from router to iMac is about 200 ft. Long, I know, but historically I have had no problems. Cable company cut through my original underground wire (CAT 6, I believe), which worked perfectly. They replaced it with another underground wire (CAT 5) and there has since been a latency issue and a decrease in download (from 30+Mbps to 10Mbps).

    I moved iMac indoors next to router and attached 4 ft cable. Latency of Internet throughput improved from 60 secs to 20 secs) but no increase in download speed. Unplugged wire and tried WiFi, which instantly gave me 35+Mbps. This would indicate to me that I have a damaged Ethernet jack or internal wire. What do you think?
     
  11. Galumph thread starter macrumors newbie

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    Aug 21, 2015
    #11
     
  12. Galumph thread starter macrumors newbie

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    Aug 21, 2015
    #12
    I did both these things and it got me back on track, namely, I still have a latency issue for Internet connect kick-in & my download is still stuck at 10Mbps, but I can consistently connect again. Thanks much. As you'll see in another response I posted, my WiFi works just fine, so I think you may be right about connector damage, even though I cannot see it. Might also be an internal wire, I suppose. So my next step might have to be getting that hardware replaced. Can't rely on WiFi because of the distance of the iMac from router (200+ ft). But I'm getting there (?)
     
  13. filmak macrumors 6502a

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    between earth and heaven
    #13
    As a temporary solution try to connect a router (a 2nd one) to your ethernet cable instead of the iMac and use wifi.
     
  14. Galumph thread starter macrumors newbie

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    #14
     
  15. Galumph thread starter macrumors newbie

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    Aug 21, 2015
  16. Galumph thread starter macrumors newbie

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    Aug 21, 2015
    #16
    I took your advice & just bought another wifi router. Works perfectly, everything up to speed. I'm going to stick with this until I can figure out if the direct wire is a software issue. If it's hardware, I think that Ethernet port is part of the motherboard, so I'm disinclined to change that out.

    Thanks so much Filmak. Also thanks to Fishrrman, InAustralia and matreya for all your suggestions.
     
  17. BrettApple macrumors 65816

    BrettApple

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    Apr 3, 2010
    Location:
    Heart of the midwest
    #17
    After reading the thread, it does sound like a bad ethernet port and/or NIC (built in). A couple easy ways to get around it would be a Thunderbolt to gigabit ethernet adapter (2011+ iMac), or even a USB to ethernet adapter (only 100 Mbps though). As noted, WiFi is another solution, just the more complex one. But if it's stable and working I'd just keep it.

    It's not uncommon for NICs to go bad. I've seen a few myself. Some are known issues on certain motherboards, others have been taken out by lightning hitting a line and some just plain don't work right.
     
  18. Galumph thread starter macrumors newbie

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    Aug 21, 2015
    #18
    Yep. I get a lot of rain where I am, so it's always possible I got a lightening zap when I wasn't looking. Even though I've got everything (including Ethernet) running through a fairly beefy APC, that's no guarantee. If I could verify it's surge damage I should be able to get APC to pay for my motherboard.
     

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