Beginner needs help. *SOME* https sites inaccesible through router ???

Discussion in 'Cisco' started by big chris, Jan 18, 2004.

  1. big chris

    big chris Guest

    I have a CISCO 700 series (775) router which connects the network card on my
    PC to my home highway ISDN with BT Internet. We have no ADSL in the town
    where I live

    For months, all has been working just fine. I click on my IE5 icon, the PC
    gets the router to connect to the ISP and my home web page opens. I can
    access all web pages, use outlook to send/receive mail, ftp transfers etc.
    etc. wonderful. If inactive for ten minutes it disconnects, great.

    Last week I found that I cannot open my online banking web page. I click on
    the favourites link (or type in the address manually) and the page just
    hangs. IE5 shows opening page https:// ibank.xxxxxxxx etc at the bottom but
    nothing else happens. Even the page title at the very top has not changed.
    This does not happen with all https sites, most are O.K. (PAYPAL also seems
    to have this trouble, but only on some of the pages).

    If I power down the router (Mains on/off switch) and then start her up again
    all works fine for the first time it connects. However, after disconnecting
    (either through timeout or forcing a disconnect) then the next time I try I
    get the same problem.

    If I leave all the settings the same in the router but change the ISP (to a
    pay as you use provider) by editing the dial up number, user name and
    password, then all seems to work just great.

    If I use the internal modem of my PC with dial up networking to connect to
    BTInternet, all works just fine.

    In summary the problem only occurs if the following are true:-

    Access is through the router.
    The router is dialling into BTInternet.
    The router has been online and disconnected at least once since last
    powered-up.
    Some, but not all, https sites. Particularly my homebanking site.

    Does anybody have any ideas as this is driving me completely mad.

    I am just a capable home hobbyist, not a network administrator, so please
    not too technical.

    Thanks in advance

    Chris
     
    big chris, Jan 18, 2004
    #1
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  2. :I have a CISCO 700 series (775) router

    :Last week I found that I cannot open my online banking web page. I click on
    :the favourites link (or type in the address manually) and the page just
    :hangs.

    Try lowering your MTU.
     
    Walter Roberson, Jan 18, 2004
    #2
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  3. big chris

    Masud Reza Guest

    Hi:

    Do you think this can have something to do with filtering of ICMP
    uncreachable messages (which might break TCP MTU Path discovery) ?

    Masud
     
    Masud Reza, Jan 18, 2004
    #3
  4. big chris

    big chris Guest

    I'd never heard of MTU until your reply. After a few hours research on the
    internet, I think I understand it. After a couple of attempts with regedit
    in the registry I found a utility to do what was required. My MTU is now
    1492 and my MSS is 1452 and all seems to be working fine- - - - so far!

    Thanks for your guidance
    Chris
     
    big chris, Jan 18, 2004
    #4
  5. big chris

    big chris Guest

    I was wrong. All was not well, still some troubles. Further reading lead
    me to beleive that there is a BT recommendation that the MTU be set to 1458.
    Tried that and all is now (after an hour or so browsing) O.K. MSS at 1418.
    Next I intend to play with my Default Receive Window (RWIN) to see if I can
    get some improvements.

    Rgds
    Chris
     
    big chris, Jan 18, 2004
    #5
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