Sunday, February 24, 2008

Weird connectivity problems

(Gee, I almost found myself saying "issues" in the post header. Don't you hate the new use of "issue" to mean "problem"?)

The connectivity problems referred to in the title are not to this site. As you can see, here I am. Ta-da! I also have e-mail and can connect to nearly all of my usual Internet sites. However, I suddenly (as of yesterday morning) cannot connect to my beloved group blog, to which I am a contributor, What's Wrong With the World.

By asking all my friends to try it and see if they can connect, I have narrowed down the problem to, apparently, my own house. My neighbor across the street has the same ISP that I do, and he can get the site.

I found this nifty article that may diagnose the problem. If so, we'll have to call in an expert. (I hope our physically local expert is available; he isn't always.) It says "only experienced Windows-savvy users" should attempt the workaround described, so I think we'll probably not try it ourselves. If this should turn out to be the problem, the mystery is why it suddenly arose yesterday morning, when nothing had changed in our local configuration.

Anyway, to all my many fans, I will be able to blog only here for a while, not at WWWtW, until it's all back up and running. One always hopes, with a trace of superstition, that the problem will just "fix itself." Maybe I'll wake up again tomorrow and it will all be better. Evidently (according to the article) that could actually happen if various servers started sending smaller "packets" that could fit down the "tunnel" of my router. Or something.

Update: The problem appears to be our local wireless router. When we plug the cable modem directly into the computer I use, the problem goes away. All sites become available. Unfortunately this means that no one else can use the Internet from a laptop at the same time. So for the time being, the cludge is that when no one else needs to use the Internet, I can switch the cables, reboot the computer (it doesn't work otherwise), and then go wherever I want on the Internet. When the wireless router is needed, we switch the cables back. Then I can come here, do e-mail, go most places, but not go to a few sites, including What's Wrong with the World. That's until we get an expert out here to find a better workaround. All most odd. I have a feeling some Bright Lad changed a packet size setting somewhere out there in cyberspace overnight between Friday and Saturday.

Update #2: Problem solved. The connection problem was indeed, as the article I linked above suggests, fixed by changing the MTU setting on my Linksys router down to 1492. The mystery that remains is why this should suddenly be necessary now. As far as I know, the setting has always been the factory-standard 1500, and this has never been a problem before, for over a year and a half. I've certainly never touched it before. I keep my ignorant hands off that stuff as much as possible. Anyway, thanks to Zippy and to Todd McKimmey for patient help and advice over the weekend. And thanks especially to Todd for pointing out to me what the linked article is not clear about and what I in my ignorance would have overlooked: If the problem is with the router, then the MTU setting that needs to be changed is the one on the router, not the one in the registry of the desktop computer. Of course. But it wouldn't have occurred to me. So just remember, if this esoteric problem should plague your Internet connection, the magic number is...1492.


Anonymous said...

You are welcome for my useless advice which could easily have diverted your attention from the real problem for hours, had you let it do so. Lydia + Google: better than a whole troop of the Geek Squad.

And good show to Todd for asking the right question.

Lydia McGrew said...

:-) :-)

When the evidence is messy, there's always a ton of guesswork involved. My attention was riveted on this possibility because the symptoms sounded very similar. As Tim said, the likelihoods were good. The prior wasn't very good though, given the sudden appearance of the problem, which still remains unexplained.

It's a fascinating thing to see how priors vs. likelihoods play out in daily life. For example, I have a theory that likelihoods should drive diagnosis but that priors should be governing when you are looking for a physical object that has been misplaced. Time and again I find a misplaced toy or other item by going back again and again to the cupboard or box where I know it _should be_. Other people are more inclined to give up and say, "But I looked there already," which is reasonable as far as it goes. I used to do the same thing as a kid and could never figure out why Mom was so much better at finding things.

In this case, though (not being a matter of finding a lost car key or toy), the likelihoods were a better guide than the priors.

The perfectly rational agent, of course, never has to choose on this, because his probabilities always put it all together just right. But none of us is the perfectly rational agent, unfortunately. :-)

Unknown said...

I am at a loss. My problem is like yours. It's in the Wireless router. When I take it out and just go directly to the cable modem, Jeff's site comes up no problem. However, I tried the MTU 1492 solution, but no go. I should point out that his address comes up in the bar, but it says the page cannot be displayed. So it seems it is going to the site, but not displaying it. Any thoughts?

Lydia McGrew said...

If the 1492 solution didn't work, nothing else I can think of is likely to. Especially since I'm just a "user," not a computer geek in any sense at all. I'm assuming you definitely changed the MTU on the router, not on the computer, right? If you unplug or reset your router, it may change it back to the factory setting of 1500.

The other things that have occasionally helped me with connection stuff were just dumb things: A hard reboot is the number one dumb thing I try. Then having Internet Explorer test your connection and fix it if it can. (IE may tell you to reset your router if it finds a problem, but that may not matter if the 1492 thing isn't helping anyway.) Then there's the "repair connection" function to try on the control panel. Oh, one other dumb thing: Try Mozilla Firefox. It happens from time to time that sites come up on Firefox that won't come up on IE. The problem usually goes away after a few days, but meanwhile, Firefox is a good workaround.

Needless to say, none of these things did the slightest good for my router problem, but I mention them since you already tried the one that actually fixed mine.

Todd had me do several things with tracert; that demonstrated (I think this is correct) that there wasn't a big router down somewhere out in the world and that it wasn't a DNS problem, because it pinged just fine and didn't get stuck on tracert, and the final address and everything was the same whether I did tracert with the router or without it. I don't know if you could find out any useful information that way.