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  1. #1
    Super Moderator BATcher's Avatar
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    DNS being blocked by my router

    Normally the ethernet connection is: PC(s) -> old Buffalo AirStation router -> cable modem -> "The Internet".

    My ISP has had some hardware maintenance done over the weekend, and the external IP address given to the device connected to the cable modem has changed, everything has been rebooted, and so on.

    Currently I can only connect to the Internet if I bypass the router, and connect directly PC -> cable modem. <UL><LI>With the router in the path, DNS doesn't work, and that still applies even if I specify DNS server IP addresses in the Network Connection settings on the PC<LI>With the router bypassed, DNS works whether or not I specify DNS server IP addresses in the Network Connection settings on the PC[/list]Presumably 'something' in the router settings is preventing the automatic assignment of DNS server IP addresses from the cable modem, and not allowing these DNS server IP addresses from the PC. (I suppose it is possible that this 4-year-old router has failed, partially.)

    Where should I be looking in the router to find what the problem is? As far as I can see, anything relating to DNS is set to 'automatic'...

    And is there any PC command which will assist (other than IPCONFIG /ALL !)?

    Thanks
    BATcher

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  2. #2
    Plutonium Lounger
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    Re: DNS being blocked by my router

    Batcher,

    Does your router have a configurable firewall? That is certainly the first place I would look.

    StuartR

  3. #3
    Super Moderator BATcher's Avatar
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    Re: DNS being blocked by my router

    Some 'bits' would appear to be configurable, so I'll hunt there - thanks.
    BATcher

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    Re: DNS being blocked by my router

    Try another DNS server setting in your router. I have openDNS set as my dns server after I had problems similar to yours with Telewest Broadband. The primary dns server in my router is now 208.67.222.222, with the other openDNS as the second and Virgin Media as the third.

    HTH
    John (Unreconstructed Jacobite)

  5. #5
    Super Moderator BATcher's Avatar
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    Re: DNS being blocked by my router

    I've already tried this, with no improvement.

    I've even reset the router back to factory configuration, then tried the 'auto configure', only to be told that the connection between the router and the cable modem is probably faulty. That's with two different patch cables...
    BATcher

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  6. #6
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    Re: DNS being blocked by my router

    If you're with Virgin Cable broadband, have you considered contacting their technical support (I did it via the newsgroup at virginmedia.support.broadband.cable -- use your choice of newsreader). When I did this a couple of questions later I was in possession of a new cable modem which solved my connect problems.

    Of course maybe it is your router...
    John (Unreconstructed Jacobite)

  7. #7
    Super Moderator BATcher's Avatar
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    Re: DNS being blocked by my router

    I'd be delighted to agree with you and blame the cable modem, but the fact remains that when you bypass the router, the connection works - I'm typing this in that configuration!

    I'm not sure I've got the patience to tackle Virgin Media Technical Support...
    BATcher

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  8. #8
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    Re: DNS being blocked by my router

    Do you know anyone who would lend you a different router for long enough to do some simple testing. This might save a lot of wasted time.

    StuartR

  9. #9
    Super Moderator BATcher's Avatar
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    Re: DNS being blocked by my router

    Thanks, Stuart - you pushed me into talking to someone from my work's Technical Support, who said that a Blueyonder engineer had told him that the trick with this sort of problem was to power off the cable modem and disconnect the coaxial cable from its rear (not something you'd think of doing, or could give a good reason for it working!), then put everything back together, powering up in the usual sequence cable modem -> router -> PC.

    And whaddyaknow, it worked immediately, and I even got back my original external IP address!

    All I need to do now it to reconfigure the router - and to determine why I had forwarded port 113 to an IP address with no connected PC (192.168.11.254)...
    BATcher

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  10. #10
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    Re: DNS being blocked by my router

    That makes as much sense to me as it does to you!

    I can't imagine why you would be accepting incoming connections on Port 113 - I would check very carefully to be sure that you don't allow admin access to your router from the Internet side.

    StuartR

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    Re: DNS being blocked by my router

    It is not an unknown issue on this side of the pond either. I have cable broadband and periodically now I have to do the same procedure. I used to yell and curse then call the cable provider (Charter) technical support (or the sequence could've been reversed <img src=/S/grin.gif border=0 alt=grin width=15 height=15>). That was always the first thing they had me do. Now it is the first thing I do and almost always saves me a call.

    Joe
    Joe

  12. #12
    Super Moderator BATcher's Avatar
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    Re: DNS being blocked by my router

    Stuart

    If you believe Steve Gibson, it's to do with IDENT (and I note that my router has a tick box to block IDENT, anyway!).
    BATcher

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  13. #13
    Super Moderator BATcher's Avatar
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    Re: DNS being blocked by my router

    Joe

    So why didn't you tell me to do this? <img src=/S/evilgrin.gif border=0 alt=evilgrin width=15 height=15>

    And, more importantly, could you explain why taking out the coax connection from the back of the cable modem should give a different result from powering it down? [puzzled]
    BATcher

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  14. #14
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    Re: DNS being blocked by my router

    Just as a matter of interest, can you clarify what the 'coax' cable is for?

  15. #15
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    Re: DNS being blocked by my router

    To coax the electrons out of the internet tubes into the computer! <img src=/S/innocent.gif border=0 alt=innocent width=20 height=20>

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