Local Area Connection: A Network Cable is Unplugged

By misterwinter
Aug 17, 2008
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  1. Hello everyone,

    This is my first post. I'm looking forward to becoming a member of this community.

    Here is my problem. I'm working on a Windows XP Desktop (Dell), which is connected to a cable modem using an ethernet cable. I also have a Windows Vista Notebook (HP) which connects to the Internet (my secure network) wirelessly.
    I use Time Warner Roadrunner as my ISP.

    A month or so ago, Time Warner contacted me and asked if I wished to "upgrade" my Internet service/speed for a nominal fee (I think it was $10 per month). As I am self-employed and frequently upload/download large files for my business, I decided that this was worth the expense. So I agreed to make the upgrade, which was done entirely on their end by resetting my modem (whole process took about 30 seconds).

    Since that time, I've had nothing but problems with the wireless connection on the Notebook. Any time I attempt to download a large file on to that computer (again, all done wirelessly), the download fails and I lose my Internet connection on that unit (e.g. the small globe icon in system tray which indicates that I am connected to my network disappears and is replaced by a red 'x' or the yellow 'alert' icon.

    At the same time this occurs, I get a notification on my desktop PC (the one that is connected using the ethernet cable) stating: Local Area Connection: A Network cable is unplugged. The outage usually lasts for anywhere from 15 seconds to 2 minutes before restoring itself.

    I have double, triple and quadruple checked all of my connections, and I can assure you that nothing is unplugged. Two calls to Time Warner have yielded little along the way of information or results. The first time I called, I was told by a snippy tech rep. that "obviously one of your cables it unplugged." The second time I called, I was told that the network card in my desktop was going bad and I needed to replace it.

    Although the second explanation sounds a bit more plausible than the first, I remain suspicious. Why is it that this problem first manifested itself within hours of my upgrading my Internet speed? It never occurred so much as once prior to the upgrade. And why does the problem NEVER occur (not even once) when I am downloading files to my desktop? And why do I get errors on BOTH machines when I am attempting to download large files to the wireless machine only?

    A friend—who is hardly an expert, but who is somewhat in the know—seems to think that the problem lies not within the network card but with the ethernet cable itself... that it may not be a good enough quality to handle the higher Internet speed He suggests buying a new ethernet cable and seeing if this remedies the problem. I'm not opposed to that solution, but I'd like to get other opinions before doing so.

    Thanks so much.

    Mister Winter
  2. jobeard

    jobeard TS Ambassador Posts: 13,285   +281

    First, be sure to update the firmware in the router, the NIC drivers for your wired connectons, and the wireless WiFi driver.

    Brand names and model numbers for all network devices may help here.

    I've seen cases where this symptom occurred due to the speed of the connection
    and as you have just upgraded your network capacity, this may apply to you.

    Broadcom 10/100/1000 adapters (and likely any gigabit adapter) set at 1000 flood the simple router and cause it to drop connections.

    First try setting 100mb, full duplex and if it is stable stop here

    Next try setting 100mb, half duplex and then move to

    10mb half duplex.

    If the wired desktop can run fine, the the cabling is not in question.
    The download via the wireless will run much slower than the wired connection
    and cause the router to back off -- the speed capacity up to the router is far
    greater than the wifi and the problem is in the speed mismatch.

    On my Netgear router, I can set the MTU size on the WAN Setup page.
    You should have something <= 1500. Personally I use 1492.
  3. misterwinter

    misterwinter Newcomer, in training Topic Starter

    Thank you for your reply. How is this (see above) accomplished?
  4. NetCablesPlus

    NetCablesPlus TechSpot Maniac Posts: 480

    I see no mention of a router in your post, so I am thinking that you have a combination modem/wirelessrouter device from your ISP? If that is the case, I would be suspicious of whatever 'upgrading' they did to the device during those thirty seconds of 'resetting'. It might be worth having them do it again or having them look a bit more closely at the device, since your problems started quickly after this new upgrade and their hardware device is a likely suspect since it was modified during the upgrade.
  5. misterwinter

    misterwinter Newcomer, in training Topic Starter

    I have two devices... a modem/transmitter and a modem for my phone (service also provided by Time Warner). As best I can tell, the cable runs into the room and then runs through a splitter, with one cable feeding into the "phone modem" and the other cable feeding into the "modem/wireless transmitter."

    Here's what I can tell you about the devices at-a-glance:

    "Phone modem" (not sure if I'm using the term correctly, but hopefully you catch my drift): Webstar (Scientific American) Model DPX2203 Series Cable Modem with EMTA.

    Modem/transmitter: Model number 60740EUW --- no brand or manufacturer listed that I can find anywhere on the device.

    (I just attempted to post an image, but evidently I have to have at least 5 posts under my belt before the system will allow me to do so.)
  6. misterwinter

    misterwinter Newcomer, in training Topic Starter

    I have a couple of minor developments.

    First, I've identified the equipment as the AMBIT wireless LAN cable modem. I believe that the model number is U10C019.

    I was eventually able to figure out where/how to modify the router settings as you suggested. Yesterday, I changed it to 100mb, full duplex. I thought I had the problem licked.

    But then today, I opened iTunes up on the wireless computer and it attempted to automatically download a number of podcasts that I subscribe to. Within seconds, I lost the connection and received the dreaded "Local Area Connection..." error on my desktop PC.

    So now I've taken the next step and modified the router setting to 100mb, half-duplex per your suggestion. Will report back as to whether or not this resolves the problem.

    You also mentioned "set the MTU size on the WAN Setup page.
    You should have something <= 1500. Personally I use 1492."

    I'm not sure how to access/change this setting or how to access the WAN Setup page. Could you please advise?

    Thank you.
  7. misterwinter

    misterwinter Newcomer, in training Topic Starter

    Well, it appears that 100mb, half-duplex did not do the trick either. Opened iTunes on the notebook and, once again, as it attempted to download a couple of Podcasts, I lost my connection and got the "Local Area Connection..." message on my desktop.

    I can go ahead and try the 10mb half-duplex option, but it occurs to me that this problem seems to occur almost exclusively with iTunes as it attempts to download Podcasts. Any thoughts on this?
  8. jobeard

    jobeard TS Ambassador Posts: 13,285   +281

    I had to go all the way to 10mb-halfdup to get mine to work
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