my dsl works fine but I can't reach one website that I know is not down. what can I do?

September 28, 2009 2:57 PM

my dsl works fine but I can't reach one website that I know is not down. what can I do?

I'm with crappy provider x and they have given me their no-name crappy wireless router y. I set it all up and it pretty much works aside from them filtering gnutella (thankyouverymuch, grrr) with one exception:

a certain website I am trying to access times out all the time. no response. now I have my iphone right next to me and I know this site is up. I can see it from my office no problem. I even spoke to its owner, who was very interested but couldn't figure out why I had this problem. enable a proxy like hotspot shield and again no problem whatsoever. alas, the proxies I know are too slow to be of any use for me.

I have tried to ping the site without success and a recent traceroute kind of dropped off around step seventeen at oakland1.level3.net, which I presume to be some kind of backbone.

so I'm lost. what can I do here?

also: what kind of halloween costume should I wear?

posted by krautland to computers & internet (18 comments total)

Try changing your DNS server to 4.2.2.1 (Verizon's). You also may just need to flush the resolver cache.

You should be Zombie Hitler wearing a dress for Halloween.
posted by Burhanistan at 3:07 PM on September 28 [1 favorite has favorites]

If you can't ping the site and a tracert drops out partway through, it's almost certainly a routing problem. If you connect your iPhone to the wireless network instead of over 3g or EDGE, does it then stop being able to load the site?

My (UK) ISP was experiencing this with large numbers of websites a few months back, but once they'd figured out what'd gone wrong they were very efficient at sorting out all their routing issues. You don't mention having contacted the ISP, is this because you haven't or because they're crap and didn't fix it when you did?
posted by fearnothing at 3:10 PM on September 28

Also, did you try this site to see if your site was actually up?
posted by Burhanistan at 3:10 PM on September 28

Addendum: that should read "if you are unable to ping the site's IP". If you have just been pinging the site's URL it could well be DNS. If that's the case, look up the IP using this handy little tool, and try pinging that instead.
posted by fearnothing at 3:12 PM on September 28

If you connect your iPhone to the wireless network instead of over 3g or EDGE, does it then stop being able to load the site?
nope, in that case it times out as well.

Also, did you try this site to see if your site was actually up?
yeah, it's just me.

you have just been pinging the site's URL it could well be DNS. If that's the case, look up the IP using this handy little tool, and try pinging that instead.
I did now enter the ip address into my browser and once again no luck.

sooo verizons dns and zombie hitler?
posted by krautland at 3:15 PM on September 28

Ask your provider to check and fix the problem. They might not be aware of it, but it's something they can and should do. Mine did.
posted by oxit at 3:15 PM on September 28

as oxit said, you need to contact your provider. If the site was loading from IP, but not URL, it would mean a DNS problem. ISP should fix this, but using alternate DNS would be a workaround. Since it's not responding to either, it means it's a routing problem. There may be a workaround, but if so I do not know it.
posted by fearnothing at 3:18 PM on September 28

I was having a similar problem, but with only one of the computers on my LAN. After banging my head against the routing tables, I noticed that peer guardian was on. :oops:
posted by low affect at 3:34 PM on September 28

Path MTU discovery.
posted by arimathea at 3:39 PM on September 28

Try open OpenDNS in your router and see if it has any effect.

Zombie Westerwelle?
posted by chillmost at 3:48 PM on September 28

the site is not loading from IP or URL.

Ask your provider to check and fix the problem.
oh, you have no idea what a world of pain their customer service department is. me being in germany, they also charge you per minute of every call. no 0800 number here.

Zombie Westerwelle
well, that at least would get me beaten up slightly less than if I were to go as zombie hitler.
posted by krautland at 4:45 PM on September 28

Are your computer's IP address and the IP address of the site you can't connect to within the same Class-C subnet? As in, "xxx.xxx.xxx.yyy" where the x's are the same numbers.
posted by bizwank at 5:02 PM on September 28

2nd'ing arimathea's suggestion of MTU size. If you can ping the server (by IP or URL), or if you can't but a traceroute gets fairly close, try reducing your MTU (or following the instructions on that page).

Basically, path MTU discovery is a sorta crappy hack that should maybe work, but often doesn't. Why so many home routers (and servers) assume it works, I don't know.

(One other potential possibility is an incorrect netmask, though that's unlikely if your using your ISP's pre-configured router and install disk. I one spent literally weeks chasing why I couldn't access a particular website, before discovering I'd put 192.168.1.0 in my netmask instead of 255.255.255.0. I still don't know why all the other sites worked ...)
posted by Pinback at 5:11 PM on September 28

hm. I did change my DNS to verizons and flushed my resolver cache via

lookupd -flushcache

(I'm on osx 10.4.11) and still nothing. weird.

the router came without an install disk. it is administered through my browser. works pretty well but alas I have no clue what causes the site to be inaccessible to me. I forgot to mention: it's not always down here, it's down about 95% of the time, the rest it's just slow as hell.

netmask is 255.255.255.0.

I don't get what to enter into terminal in regards to the path MTU thing but I'm not using a PPPoE login/pwd combination if that is important at all. there is an option to enter that but I didn't since my dsl just worked.
posted by krautland at 5:54 PM on September 28

Not an answer but…I once had trouble loading images at apple.com. The site text and structure would load (from http://apple.com) but all images came from http://images.apple.com and did not load. After chasing the same tail for hours by email and phone I happened to mention it to a field technician (from the phone company/DSL provider) who was on site for an unrelated matter. He happened to have a new DSL modem on his truck…we plugged it in and…you guessed it. Problem solved.

Halloween? I got nothing for you.
posted by Dick Paris at 6:38 PM on September 28

MTU can be an issue on any interface or connection type, not just PPoE. It's quick & worth a try:

Mac OS X 10.4 or later: How to change the MTU for troubleshooting purposes (bottom of page)

Try it and see. Ignore the talk about Airport, unless you're connecting via wireless; it's just the example they use. You'll need to specify your actual interface name e.g. en0 for ethernet. I'd also suggest trying a fairly low value for troubleshooting purposes - you can always wind it back up to find where it starts failing.

e.g. "sudo ifconfig en0 mtu 576" will set your wired ethernet port to use an MTU of 576, rather than 1500.

Making it permanent in 10.4.x is harder (involved editing startup scripts & plist files), so let's not go there unless it works ;-)
posted by Pinback at 7:20 PM on September 28

path MTU didn't do it. I limited it to 1400 and then to 576 but no dice.

I'm on the line with customer service right now and they're telling me to consider using a different browser. gnnnnnnaaaaa....
posted by krautland at 8:41 AM on September 29

Could you try and answer my question above? I did DSL tech support for several years and have seen this problem before.
posted by bizwank at 8:12 AM on September 30