Strange problem - Cannot access a few sites through my router...

[cthorpe]

Got a puzzler for you...

So I have a Buffalo WHR-G54S router that had been running dd-wrt (http://dd-wrt.com) for more than 100 days without a reboot.  Everything was fine, then all of the sudden, I started having trouble accessing certain websites.  At this time, I know that I cannot access http://adobe.com, http://xkcd.com, and http://quantz.com. ; In addition, I have come across a few other inaccessible sites in my searches for answers to this problem, though I don't remember their names.  The sites are inaccessible on my desktop PC and my wife's laptop (both running XP) and my iBook.  If I bypass the router and plug directly into the modem, everything works fine.  Obviously, that isn't a workable solution.  I have tried resetting dd-wrt back to default settings, hard rebooting to force the internal memory to clear, reflashing the version of the firmware I was running before, flashing a newer version, and even flashing a different alternative firmware (Tomato http://www.polarcloud.com/tomato) to the router, all to no avail.  The XP installation on my desktop is about 1 week old, and I have taken steps to ensure that it remains as clean as possible.  I haven't messed with mtu's or any other network settings.

I have searched around in the Buffalo, dd-wrt, and Tomato forums and haven't seen any solutions.


Any ideas?

[f0dder]

Can you ping/traceroute the sites? Have you compared what IP is returned by DNS lookup from behind-router and directly-plugged?

[cthorpe]

Yes, I can ping and tracert from behind the router.  IPs are identical as well.  Also, this is a problem in any browser.

[tomos]

Lanux gave this link a while back when I couldnt access a certain page (that everyone else could)
no decisive conclusions but it might help nevertheless*

http://www.sitepoint.com/forums/showthread.php?t=242638
from this thread
http://www.donationcoder.com/forum/index.php?topic=2794.msg63615#msg63615

* I didnt really follow up on it because the site I couldnt reach wasnt anything of major importance
and it's only happened once since with a different site.

[techidave]

whenever we have had similar problems at school, I had to reset the MTU on the router.  Most by default are set at 1500 but that doesn't mean this is what your ISP's default is.  You could try 1492 or 1484.  It decreases by 8 from 1500.  Our ISP change it at one time and didn't tell anyone, so you can imagine the headaches we had until we figured it out.

I don't know if this is what your answer is or not but it might be worth trying.  For more about MTU's go here http://en.wikipedia.org/wiki/Maximum_transmission_unit

XP also has an individual setting but since it affects more than one machine I would say you need to change it on your router.

[tinjaw]

It is possible, but unlikely that things like MTU size are the problem. If that was the case, the problem would exist for all websites as well as any traffic.

cthorpe,

A little detective work shows that the three sites you mention all have their DNS service at easydns.com. It sounds like you might be experiencing some issues with DNS. As you run into these problem sites, see if they are also handled by easydns. I agree with f0dder that is most likely an issue of this nature.

• adobe.com
• xkcd.com
• quantz.com