Strange Internet Connectivity Issue

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Jorpho
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Strange Internet Connectivity Issue

Postby Jorpho » Mon Nov 02, 2015 4:51 am UTC

My Internet connection has a very unpleasant habit of dropping out for no particular reason, but it's proving difficult to narrow down the cause.

-Websites are completely unreachable by web browser on my Windows PC when the connection goes down.
-I have a wireless router connected to my Speedtouch router, which in turn is connected to my DSL provider. I mainly use the wireless connection with my 3DS, which also completely fails to connect to the Internet when the connection goes down.
-I also have a Mediatrix VOIP gateway box that connects my analog phone to my VOIP provider. My phone always seems to work perfectly even when the connection goes down.
-I can still bring up the web interface for the router and check connectivity when my connection goes down, and it always insists that Everything Is Fine.
-After turning the router off and back on again, everything works fine.

I'm tempted to call my ISP and see if they can figure out what is going on, but I'm kind of skeptical about how useful that will be. What could the problem be?

cphite
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Re: Strange Internet Connectivity Issue

Postby cphite » Tue Nov 03, 2015 4:20 pm UTC

Jorpho wrote:My Internet connection has a very unpleasant habit of dropping out for no particular reason, but it's proving difficult to narrow down the cause.

-Websites are completely unreachable by web browser on my Windows PC when the connection goes down.
-I have a wireless router connected to my Speedtouch router, which in turn is connected to my DSL provider. I mainly use the wireless connection with my 3DS, which also completely fails to connect to the Internet when the connection goes down.
-I also have a Mediatrix VOIP gateway box that connects my analog phone to my VOIP provider. My phone always seems to work perfectly even when the connection goes down.
-I can still bring up the web interface for the router and check connectivity when my connection goes down, and it always insists that Everything Is Fine.
-After turning the router off and back on again, everything works fine.

I'm tempted to call my ISP and see if they can figure out what is going on, but I'm kind of skeptical about how useful that will be. What could the problem be?


When this happens, are you able to see other devices on your network? For example, if you're on your PC and you have other PCs on the network, or a wireless printer, or whatever - can you see those and transfer data to and/or from them?

Also, when this happens, does Windows show a problem with the internet connection? In other words, does the icon in the notification area (lower right corner on the taskbar) indicate that you are connected but have no internet connection?

You say you have a router attached to your Speedtouch router - are both routers putting out a wireless signal? That could be a problem right there; especially if they are running on the same wireless channel. This can cause interference and result in exactly the sort of intermittent dropping that you describe. If both are transmitting wireless, check the channel settings and set them as far apart as possible; or disable wireless on one of them (preferably the one connected to the phone line, for better security).

Aside from that, you may have a bad router - either of them. Calling the ISP and having them run a diagnostic might be useful - especially while the problem is active.

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Jorpho
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Re: Strange Internet Connectivity Issue

Postby Jorpho » Wed Nov 04, 2015 12:11 am UTC

cphite wrote:When this happens, are you able to see other devices on your network? For example, if you're on your PC and you have other PCs on the network, or a wireless printer, or whatever - can you see those and transfer data to and/or from them?
To be precise, the connection is like this:

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Linksys [Wireless]
   |
Speedtouch-------Mediatrix------ComputerA
   |
ComputerB
I can start up smallftpd on ComputerB and subsequently FTP from ComputerA even when the connection is down. I can also bring up the configuration page for the Linksys when the connection is down.

Also, when this happens, does Windows show a problem with the internet connection?
Nope.

You say you have a router attached to your Speedtouch router - are both routers putting out a wireless signal?
The Speedtouch has no wireless capabilities at all.

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Jorpho
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Re: Strange Internet Connectivity Issue

Postby Jorpho » Thu Nov 05, 2015 3:03 pm UTC

Gah, stupid me.

I didn't bother to check whether ComputerA could still connect to the Internet, even when ComputerB or the Linksys seem to be incapable of doing so. (It is an obnoxiously outdated piece of tech that I should have dumped years ago.) It keeps working.

To be clear, unplugging both the Mediatrix box and the Linksys does not spontaneously restore connectivity to ComputerB.

It would be nice if this was because ComputerA (and the Mediatrix) occupied some privileged position, but no – they're plugged into ethport3. So it's still not clear what's going on here.

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Re: Strange Internet Connectivity Issue

Postby cphite » Thu Nov 05, 2015 10:10 pm UTC

It probably wouldn't hurt to call your ISP and have them run a diagnostic, preferably when the problem occurs. Aside from that, you could try running Wireshark or something like it on one of your machines and see if you can detect anything odd happening on the network before or during an episode.

My guess is that something is going wrong with the Speedtouch and that it's losing routing functionality. If I understand correctly, both ComputerA and your Mediatrix box are connected to the Speedtest via ethernet cables; have you tried swapping the ports?

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Re: Strange Internet Connectivity Issue

Postby Jorpho » Fri Nov 06, 2015 1:49 am UTC

The ISP couldn't find any problems on their end, alas.

Aside from that, you could try running Wireshark or something like it on one of your machines and see if you can detect anything odd happening on the network before or during an episode.
I've never done that before. Is there a tutorial you would suggest?

My guess is that something is going wrong with the Speedtouch and that it's losing routing functionality.
I should add that the Telnet interface for the Speedtouch keeps working. I was kind of hoping there was some cryptic arcana I might employ that would magically explain everything.

If I understand correctly, both ComputerA and your Mediatrix box are connected to the Speedtest via ethernet cables; have you tried swapping the ports?
Yes, they are using Ethernet. I suppose swapping the cables might be worth a try.

ETA: Connection went down again, so I tried swapping the cables around; afterwards, the VOIP kept on working, and ComputerB still couldn't connect – and actually, the Speedtouch status page didn't even indicate that anything changed until I restarted it again. Maybe it will keep working now.

ETA2: Nope.

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Re: Strange Internet Connectivity Issue

Postby Xanthir » Sat Nov 07, 2015 7:26 pm UTC

I have very similar problems, and have never been able to figure it out. Different devices will just... stop seeing the network, and our laptops will occasionally get "finicky" and have random connections hang for a long time (reloading will usually have the page work fine).

This has been persistent across two routers, and it's only solved by restarting the router every few weeks, so ???
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Re: Strange Internet Connectivity Issue

Postby Jorpho » Thu Nov 12, 2015 1:29 pm UTC

The connection has been oddly well-behaved this past week. The only thing that's really changed is that I've been keeping Thunderbird closed on ComputerA. As I mentioned, ComputerA is horrendously outdated and no longer particularly up to the task of even running the latest Thunderbird on XP SP3; it tends to slow to a crawl and Thunderbird frequently throws up "unresponsive script" errors. Could there be some kind of halting problem that an insufficiently-responsive computer could cause on a network, or is that just wishful thinking?

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Re: Strange Internet Connectivity Issue

Postby cphite » Thu Nov 12, 2015 8:59 pm UTC

Jorpho wrote:The connection has been oddly well-behaved this past week. The only thing that's really changed is that I've been keeping Thunderbird closed on ComputerA. As I mentioned, ComputerA is horrendously outdated and no longer particularly up to the task of even running the latest Thunderbird on XP SP3; it tends to slow to a crawl and Thunderbird frequently throws up "unresponsive script" errors. Could there be some kind of halting problem that an insufficiently-responsive computer could cause on a network, or is that just wishful thinking?


It could be... you could test by bringing Thunderbird back up again and seeing if the problem returns. You can also look in Event Viewer on that machine and see if the times of the internet outages coincide with Thunderbird problems - those popups should be in the Applications log.

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Jorpho
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Re: Strange Internet Connectivity Issue

Postby Jorpho » Fri Nov 13, 2015 3:10 pm UTC

Ah, the Event Viewer! I should have been looking there in the first place.

The System log for ComputerA turns up frequent errors along the lines of "The IP address lease 192.168.1.65 has been denied by the DHCP server 192.168.10.1". 192.168.10.1 is the IP address of the Mediatrix box, but that's not supposed to be acting as a DHCP server at all, or so I thought. Anyway, these errors seem to be in no way correlated with the network outages.

By the way, could the "QoS Packet Scheduler" have anything to do with this? Maybe ComputerA is decreeing that its packets should have priority above all others when Thunderbird starts getting bogged down? Is there some way to know what the "QoS Packet Scheduler" is doing?

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Re: Strange Internet Connectivity Issue

Postby cphite » Fri Nov 13, 2015 4:02 pm UTC

Jorpho wrote:Ah, the Event Viewer! I should have been looking there in the first place.

The System log for ComputerA turns up frequent errors along the lines of "The IP address lease 192.168.1.65 has been denied by the DHCP server 192.168.10.1". 192.168.10.1 is the IP address of the Mediatrix box, but that's not supposed to be acting as a DHCP server at all, or so I thought. Anyway, these errors seem to be in no way correlated with the network outages.


Ah, that could be your problem right there; it would also explain why the VOIP still works when the rest of your network seems to go down. While it is possible to run multiple on the same network, you need to make sure they're not competing with one another. Generally they'd be covering different IP ranges. If yours are covering the same range, it's possible they're conflicting.

And the nasty part is, while you'll see messages about leases being denied, you typically won't see anything about the actual conflicts because it's all happening between your network hardware.

By the way, could the "QoS Packet Scheduler" have anything to do with this? Maybe ComputerA is decreeing that its packets should have priority above all others when Thunderbird starts getting bogged down? Is there some way to know what the "QoS Packet Scheduler" is doing?


It's possible, but really not likely. QoSPS is only supposed to allocate 20 percent of bandwidth for a given program; and unless you're transferring large attachments, the bandwidth for email should be pretty slim.

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Re: Strange Internet Connectivity Issue

Postby Jorpho » Sat Nov 14, 2015 4:02 am UTC

cphite wrote:The System log for ComputerA turns up frequent errors along the lines of "The IP address lease 192.168.1.65 has been denied by the DHCP server 192.168.10.1". 192.168.10.1 is the IP address of the Mediatrix box, but that's not supposed to be acting as a DHCP server at all, or so I thought. Anyway, these errors seem to be in no way correlated with the network outages.
Ah, that could be your problem right there; it would also explain why the VOIP still works when the rest of your network seems to go down. While it is possible to run multiple on the same network, you need to make sure they're not competing with one another. Generally they'd be covering different IP ranges. If yours are covering the same range, it's possible they're conflicting.
But the thing is, it's not supposed to be acting as a DHCP server, and I'm not sure why it would be. ComputerA still picks up the router at 192.168.1.254 for the gateway. To be clear, 192.168.10.1 is the "LAN" IP address of the Mediatrix and (I think) is only supposed to be visible to ComputerA (which is plugged into the corresponding "LAN" port on the Mediatrix). The Mediatrix happily gets its "WAN" address from the Speedtouch.

According to its web interface, the DHCP Pool of the Speedtouch is already 192.168-1.64-192.168.1.253.

I hope this makes some degree of sense – the Mediatrix actually has a weird configuration bug that I'd love to get to the bottom of.

By the way, could the "QoS Packet Scheduler" have anything to do with this? Maybe ComputerA is decreeing that its packets should have priority above all others when Thunderbird starts getting bogged down? Is there some way to know what the "QoS Packet Scheduler" is doing?
It's possible, but really not likely. QoSPS is only supposed to allocate 20 percent of bandwidth for a given program; and unless you're transferring large attachments, the bandwidth for email should be pretty slim.
Shucks, that would be too easy.

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Re: Strange Internet Connectivity Issue

Postby Jorpho » Thu Feb 04, 2016 6:24 am UTC

I never got to the bottom of this.

I thought I'd mention that sometimes before everything in Firefox starts turning up "server not found" messages, I do get a blank page with an empty box at the top. It occurred to me I could use the dev tools to inspect what this empty box was supposed to be. Here's what turns up:

Code: Select all

<parsererror xmlns="http://www.mozilla.org/newlayout/xml/parsererror.xml" hasBrowserHandlers="true">XML Parsing Error: unexpected parser state
Location: jar:file:///C:/Program%20Files%20(x86)/Mozilla%20Firefox/browser/omni.ja!/chrome/browser/content/browser/aboutNetError.xhtml
Line Number 439, Column 54:<sourcetext>        &lt;div id="ed_netTimeout"&gt;&amp;netTimeout.longDesc;&lt;/div&gt;
-----------------------------------------------------^</sourcetext><style xmlns="http://www.w3.org/1999/xhtml" type="text/css">:root div[style="width:300;height:250px;margin-bottom:10px;"],
:root .powBy,
:root #fb_mtutor,
:root .ad-banner,
:root #main-content &gt; [style="padding:10px 0 0 0 !important;"]
{display:none !important;}</style><style xmlns="http://www.w3.org/1999/xhtml" type="text/css">:root div[style="width:300;height:250px;margin-bottom:10px;"],
:root .powBy,
:root #fb_mtutor,
:root .ad-banner,
:root #main-content &gt; [style="padding:10px 0 0 0 !important;"]
{display:none !important;}</style></parsererror>
Does this mean anything to anyone? "#fb_mtutor" lopks mighty suspcious, but Google tells me nothing.

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Re: Strange Internet Connectivity Issue

Postby phlip » Tue Feb 09, 2016 12:58 am UTC

Having aboutNetError.xhtml throw a parsing error is a problem I used to have in the past, though not for some time. Is that a current version of Firefox?

The extra "<style>" tags in the <parsererror>, though, is not something I've seen before, and smells of adware to me. Some Fx extension/addon trying to inject crap into the page, and breaking on the fact that the XML parser error page isn't HTML, getting confused, and breaking the page (I'm a little surprised you end up with just a blank page with an empty box, trying to experiment with injecting <style> tags into <parsererror>s doesn't seem to break it that badly, but who knows what else it's doing). I can't find much in Google about this particular block, either.

Basically: the error message it's trying to show is some sort of timeout message (makes sense if your network goes down while it's trying to load a page - the load that's happening when it goes down gets a timeout error, any loads after that get server-not-found), except the XHTML file for that error message is broken so instead it's trying to show you the parser error. Except then that error message is being broken by the adware. So that blank box is caused by an error that happened trying to display the error message for the error that happened trying to display the error message for the error you're having with your network.

Code: Select all

enum ಠ_ಠ {°□°╰=1, °Д°╰, ಠ益ಠ╰};
void ┻━┻︵​╰(ಠ_ಠ ⚠) {exit((int)⚠);}
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Jorpho
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Re: Strange Internet Connectivity Issue

Postby Jorpho » Tue Feb 09, 2016 2:42 pm UTC

I was kind of hoping that the box might be the result of some kind of last gasp generated by the router, but Googling suggests that it is indeed not unknown for Firefox to generate very similar messages (albeit nothing exactly like this one), particularly when timing out. Oh well.

No harm in running an adware scan, I guess, though I can't imagine it would turn anything up.

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Re: Strange Internet Connectivity Issue

Postby cphite » Thu Feb 11, 2016 3:28 pm UTC

My best guess at this point is that your problem is related to the Mediatrix box trying to act as a DHCP server. I don't know why it'd be doing that, or if there is some setting on it that you can use to disable that functionality; but if it is, it could explain why connections are timing out for you.


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