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Really Weird Internet Connection Issue

CronusCronus Registered User regular
edited September 2010 in Moe's Stupid Technology Tavern
I've been having a very weird connection issue that I'm hoping someone here can shed some light on.

One evening getting home from work and pulling my chair up to my desk I discovered that I couldn't access the internet. The next morning with it still down I called Qwest and during the conversation we found out that I could access google and other google sites such as youtube, but nothing else. Surprisingly removing my router from my network and plugging my switch directly into the modem fixed the problem. So then I ordered a new router thinking that would be that.


However with the new router, both wired and both on the latest firmware and both from different companies, I have the same problem. After some more Googling I discovered that this is a surprisingly common problem and that changing the MTU on my computer from 1500 to 1492 solves the problem. What could cause the internet access for the entire network to suddenly need a different MTU?


Is there anything I can do besides switching to Comcast? I don't want to have to worry about the MTU of all the devices on my network. Especially after 3 years of internet access without any problems like this. And just to be clear this problem occurred simultaneously on all the computers on my network and with two different routers.


I appreciate any information you can offer. Thanks.

Cronus on
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"Read twice, post once. It's almost like 'measure twice, cut once' only with reading." - MetaverseNomad

Posts

  • GreenishGreenish Registered User regular
    edited August 2010
    MTU means Maximum Transmission Unit. It tells your devices how large the data chucks (called packets) being sent to you should be. Somewhere in your connection you are getting corrupt packets and that will give you connection problems. The source of the data will try to resend until either it goes through or the source gives up and your connection drops. Different sources will retry a different number of times (thats why some persistent sites will still come through). Setting the MTU to a lower setting means the packets sent to you are smaller and you are more able to avoid corrupt packets, but your connection speed suffers slightly as a result.

    I'd log into your router and modem and make sure they are using the same MTU settings. If you still get the problem, swap out your ethernet cables between switch and router and router to modem to make sure they aren't corrupting your packets. Also check the line between your modem and the wall. Qwest runs DSL so get the phone company to come by and test your phone lines. Old phone lines can cause data corruption and the phone company is obligated to service phone lines (for free) until they reach the box on the side of your home.

    If that doesn't work then changing to a cable ISP might be the solution. Good Luck!

  • CronusCronus Registered User regular
    edited August 2010
    Thanks for the info. Changing the MTU size in my router does work and saves me from having to make the change to every computer.

    The corruption problem you mentioned doesn't seem like an issue here. Sites that do come up are always the same, google sites, and they always come up immediately like normal. And others never do and the browser continually tries to connect until I close it. There is never an error message.

    Also I'd still love to know what caused the problem. Do you still think corruption could be an issue after reading the above paragraph?

    camo_sig.png
    "Read twice, post once. It's almost like 'measure twice, cut once' only with reading." - MetaverseNomad
  • GreenishGreenish Registered User regular
    edited August 2010
    Do you log in to some of these sites you are visiting? Anything that modifies the standard http connection for things like secure connections adds or removes data to normal packets which changes the MTU slightly depending on what the setting on your end is.

    If things are working now that you changed the MTU settings on your router and you are happy with the result then I'd say roll with it. Signal degradation would explain why it was working before but not now. As the signal passes through each section of cable it gets weaker and weaker and you won't notice it until one cable gets just weak enough that the data comes through as corrupt. You can compensate with settings or try to boost the signal with either a new cable or with less cable. Thats what leads me to believe that when you removed the section of cable with the router attached, things worked like they should.

  • CronusCronus Registered User regular
    edited August 2010
    No I don't log into any of the sites. My main 3 I used when testing were Google, Bing, and Yahoo. Google always loaded normally and Bing and Yahoo never did. Along with almost any other site such as this. And I was never logged into any site that loaded.

    The thing is that I've probably tried to load those 3 sites 100 times troubleshooting this problem and whenever I was connected through the router I had the exact same issue where Google, or a Google search, or a Google map would load normally, but everything else would forever try to load. Never failing of never succedding. I can try and swap out the cable between the router and the modem and bring the MTU size back to 1500 or do something similar if there was something you wanted to test.

    camo_sig.png
    "Read twice, post once. It's almost like 'measure twice, cut once' only with reading." - MetaverseNomad
  • punkpunk Registered User
    edited August 2010
    I had a similar issue at a service provider I worked at about a year ago. We were using GRE tunnels over a multilink PPP connection. The GRE tunnel added additional overhead to packets being sent so that instead of staying within 1500 they jumped to 1580, which resulted in fragmentation. This was limited to a specific vendor as well, as we could set the MTU and MRRU on one vendor's equipment and resolve the problem entirely, but the other vendor's equipment wouldn't go any higher than 1520.

    We found that some websites did not appreciate that much fragmentation and simply wouldn't load. You'd either have sites that didn't care and would load instantly, sites that would take fooooooooooooooooooooooooooreeeevvveeerrr or sites that simply wouldn't load at all. This made troubleshooting the issue just...hilarious. But in a "haha, sad" kind of way.

    I would not put it past Qwest to make a change on their network somewhere that affected you in a like fashion. You'd be pretty hard pressed to get past Tier 1 on the problem, too, as everything is solved by rebooting your modem. If setting your MTU lower resolved the issue and you're OK with that, like Greenish said, "roll with it."

  • CronusCronus Registered User regular
    edited August 2010
    punk wrote: »
    I had a similar issue at a service provider I worked at about a year ago. We were using GRE tunnels over a multilink PPP connection. The GRE tunnel added additional overhead to packets being sent so that instead of staying within 1500 they jumped to 1580, which resulted in fragmentation. This was limited to a specific vendor as well, as we could set the MTU and MRRU on one vendor's equipment and resolve the problem entirely, but the other vendor's equipment wouldn't go any higher than 1520.

    We found that some websites did not appreciate that much fragmentation and simply wouldn't load. You'd either have sites that didn't care and would load instantly, sites that would take fooooooooooooooooooooooooooreeeevvveeerrr or sites that simply wouldn't load at all. This made troubleshooting the issue just...hilarious. But in a "haha, sad" kind of way.

    I would not put it past Qwest to make a change on their network somewhere that affected you in a like fashion. You'd be pretty hard pressed to get past Tier 1 on the problem, too, as everything is solved by rebooting your modem. If setting your MTU lower resolved the issue and you're OK with that, like Greenish said, "roll with it."

    That's very interesting and in regards to your last paragraph rebooting my modem doesn't solve anything. Though I do agree that I'd have a hard time getting past Tier 1 tech support. I also don't think that my blood pressure could handle that conversation with them as it would surely take hours and I'd probably be hung up on at least twice.

    I'm not ok with the MTU change, but I don't see much of a choice at this point short of switching providers. I did find a couple email address for Qwests executive customer service so I may take my first post from this thread and send it as an email to them.

    Either way I think that this change is still better than using Comcast for internet access.

    camo_sig.png
    "Read twice, post once. It's almost like 'measure twice, cut once' only with reading." - MetaverseNomad
  • punkpunk Registered User
    edited August 2010
    Cronus wrote: »
    punk wrote: »
    I had a similar issue at a service provider I worked at about a year ago. We were using GRE tunnels over a multilink PPP connection. The GRE tunnel added additional overhead to packets being sent so that instead of staying within 1500 they jumped to 1580, which resulted in fragmentation. This was limited to a specific vendor as well, as we could set the MTU and MRRU on one vendor's equipment and resolve the problem entirely, but the other vendor's equipment wouldn't go any higher than 1520.

    We found that some websites did not appreciate that much fragmentation and simply wouldn't load. You'd either have sites that didn't care and would load instantly, sites that would take fooooooooooooooooooooooooooreeeevvveeerrr or sites that simply wouldn't load at all. This made troubleshooting the issue just...hilarious. But in a "haha, sad" kind of way.

    I would not put it past Qwest to make a change on their network somewhere that affected you in a like fashion. You'd be pretty hard pressed to get past Tier 1 on the problem, too, as everything is solved by rebooting your modem. If setting your MTU lower resolved the issue and you're OK with that, like Greenish said, "roll with it."

    That's very interesting and in regards to your last paragraph rebooting my modem doesn't solve anything. Though I do agree that I'd have a hard time getting past Tier 1 tech support. I also don't think that my blood pressure could handle that conversation with them as it would surely take hours and I'd probably be hung up on at least twice.

    I'm not ok with the MTU change, but I don't see much of a choice at this point short of switching providers. I did find a couple email address for Qwests executive customer service so I may take my first post from this thread and send it as an email to them.

    Either way I think that this change is still better than using Comcast for internet access.

    Sorry, the "rebooting your modem" part was pure sarcasm. It's the first thing Tier 1 always wants you to try, even if you've already done it.

  • windmitewindmite Registered User
    edited August 2010
    I had the same problem with Qwest back when I lived in Albuquerque. Google worked and nothing else. It drove me insane because it just goes against everything I know about computers and networks. Sorry to say while I could do things like mess with MTUs and DHCP for temporary fixes it always came back.

    I eventually switched to Comcast, which had it's own problems but at least they made sense. I could reboot the modem and if that didn't work I could just read a book and wait because I knew it wasn't anything on my end.

    For my own peace of mind I eventually decided it had to be something with DNS servers and Google was used so often it was always cached. I don't have any evidence but you could try using google's public DNS servers if you have to know. If changing MTU settings works permanently just let it go ... I got so frustrated with Qwest that when I switched and found out Comcast in my area didn't work from 7-8pm I just didn't care and made that reading hour.

  • CronusCronus Registered User regular
    edited August 2010
    windmite wrote: »
    I had the same problem with Qwest back when I lived in Albuquerque. Google worked and nothing else. It drove me insane because it just goes against everything I know about computers and networks. Sorry to say while I could do things like mess with MTUs and DHCP for temporary fixes it always came back.

    I eventually switched to Comcast, which had it's own problems but at least they made sense. I could reboot the modem and if that didn't work I could just read a book and wait because I knew it wasn't anything on my end.

    For my own peace of mind I eventually decided it had to be something with DNS servers and Google was used so often it was always cached. I don't have any evidence but you could try using google's public DNS servers if you have to know. If changing MTU settings works permanently just let it go ... I got so frustrated with Qwest that when I switched and found out Comcast in my area didn't work from 7-8pm I just didn't care and made that reading hour.

    Thanks for the info and I was thinking of switching to Comcast despite the fact that it would make my skin crawl. I do know that it's not a DNS issue as I could not connect to non-Google sites by IP as well as address. I sent an email yesterday to Qwests Executive Customer Support(woot for the Consumerist) and I'll see if I get any useful info.

    If not I may just leaves things the way they are as everything is working now. But if I have the same problem you did windmite with the problem coming back then switching ISPs would probably be my only option.

    camo_sig.png
    "Read twice, post once. It's almost like 'measure twice, cut once' only with reading." - MetaverseNomad
  • archonwarparchonwarp Registered User regular
    edited September 2010
    I've been having some similar issues with bad quality connections. I have Time Warner Cable (Road Runner Internet), and it alternates between terrible and awesome at the most inconvenient times. I've swapped out the modem twice within the last three years, as well as changing between four different routers, and I still have the problem. Should I start lowering my MTU and see if that fixes anything? It's currently at 1500, which is the default for my Linksys router and (supposedly) my ISP's default.

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  • CronusCronus Registered User regular
    edited September 2010
    My MTU problem resulted in me simply not being able to connect. It didn't affect the quality of the connection at all. You could certainly give it a try, but I don't think it'll fix the problem for you. It only takes a few seconds to change the MTU via command line. I don't know it by heart, but you can find it via google pretty easily.

    camo_sig.png
    "Read twice, post once. It's almost like 'measure twice, cut once' only with reading." - MetaverseNomad
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