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  1. #1
    Linux Guru fingal's Avatar
    Join Date
    Jul 2003
    Birmingham - UK

    ADSL router - can't connect to internet

    Hello - I've developed a nasty ADSL internet connection
    problem which goes as follows. I can't connect to the outside
    internet, but I can ping my internal network/router.
    It's a desktop box with an IP address of,
    and I connect used a wired D-Link DSL-504T router and
    a 3-Com ethernet card, which has been extremely reliable to date.

    Mandriva reports that my network is up on eth0 (in fact this
    is obviously so) but I can no longer ping any external web
    address. Indeed, my router won't connect at all, where
    previously I had no trouble. My router's log file contains
    the following info., repeated over and over. The date
    is nonsense and is (I think) a bug. I know the correct
    date because I've been clearing and checking the
    log just to make sure.
    Jan  1 05:33:13> pppd 2.4.1 started by root, uid 0
    Jan  1 05:33:13> Connect: ppp0 {--} 
    Jan  1 05:33:16> CHAP authentication failed
    Jan  1 05:33:16> Connection terminated.
    Jan  1 05:33:16> Failed to Authenticate
    I gather that CHAP is a Microsoft 'handshake
    authentification protocol' which I found out about
    accidentally while looking at other routers with a
    view to replacing this one (assuming it's faulty).
    I should explain that my net connection has been
    getting increasingly unreliable, disconnecting me
    from time to time without warning.

    I learned that if I restarted my router I could
    connect again with few problems. Something has
    started to go wrong, and it's got progressively
    worse until I'm completely off-line at home. At
    first I thought it was my ISP's fault but not now.

    Is my router really due for replacement? I dismantled
    it and had a look, but nothing is visably wrong.
    It's just a single board, and it looks fine but this
    could be deceptive. I thought I might see a
    burn-out on the surface of the board, or a loose
    wire, but no.

    Some techie stuff about my routers' settings
    which may be useful:

    Uses PPPoA
    MTU=1500 (though it defaults to 1400 ... I prefer to set
    it to 1500. Mandriva is using the same MTU)
    NAT enabled / firewall enabled
    QoS: UBR (I have no idea what this means!)
    Modulation type: GDMT
    Commects using DCHP

    As far as I know these settings are okay, but any
    advice, guidance or information gratefully received.
    Even rebooting the router does no good now.
    The router looks pretty innocent, blinking away
    on my desktop ... Nothing has changed outwardly,
    but it's funny how fragile a net connection can be!

    Note to moderator(s): Maybe this should have gone in the networking section? I'm not sure considering that I think my router might be faulty.
    I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

  2. #2
    Linux Guru fingal's Avatar
    Join Date
    Jul 2003
    Birmingham - UK
    Well ... I got it working again. It's not very reliable for some reason (a bit like an arthritic donkey on valium) but at least I can connect. The trick was to ignore the manual and use a combination of Google for further information, my brain and sheer bloody minded determination. So there you have it. Don't read the manual!

    The other thing which I found to be useful is 'power cycling'. So if you find you can't connect, just pull the plug out of the back of your router and then plug it in again. Your router will restart and perhaps ... just perhaps ... you'll get your connection back again.
    I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso

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