Strange broadband problem: email fine but web pages are slow and have no pictures

I've been investigating a very weird broadband problem for a customer.
Anyone any ideas what could have gone wrong?

The customer has an XP Home SP2 PC, connected by Speedtouch 330 modem to
Tiscali at 2 Mbps. He can connect 100% reliably and can send/receive email.
But most web pages are taking several minutes to display (with a blank white
screen until they have loaded), and when they do load, any JPG images are
missing and replaced by placeholder rectangles. Some sites such as
news.bbc.co.uk display partially (eg just the BBC News maroon banner) and
then complete the loading (without pictures) a few minutes later.

I've turned off Windows Firewall and Norton Anti-Virus. I've installed Opera
to eliminate problems with Internet Explorer. Apart from displaying the text
of pages (but not the photos) instantaneously, the symptom is the same with
0pera.

Doing a "View Source" during the "white screen" time, the HTML is truncated
as if it hasn't completely transferred.

I tried using the DOS-mode ftp to upload a variety of files (doc, pub, jpg -
a few hundred KB) to my web server and then to download them again. All
files go up OK and all except JPG transfer back down OK; the JPG only
transfers about 1KB and then stops transferring without any error message.

I can ping the sites OK. I can do a "telnet news.bbc.co.uk 80" and get a
response, suggesting that port 80 traffic isn't being blocked.

I've tested the PC on my DSL line, both using the customer's modem and my
router, and everything works perfectly.

I've tested my router on his line and the symptoms are as described above.

So it looks as if the PC and its modem are working fine, and it's the line
which is taking a long time to download HTML and is blocking JPG. Could
Tiscali have applied some sort of traffic filtering or throttling?


Tiscali got me to try a few simple tests like turning firewall and AV off,
and configuring stating DNS server addresses instead of getting them from
DHCP, and then decided that because the PC can connect to broadband and can
access POP/SMTP, it must be a PC problem - even though I said that the PC
works fine when connected to a different DSL line.

Apparently it's never worked on this phone line. They had to get a new
dedicated phone line installed a couple of months ago after the previous
one, which is also the voice line, and which had worked perfectly up to that
point, suddenly lost its DSL carrier one day and could not be made to work
again. A neighbour's DSL line also failed at the same time. All that's past
history, long before I became involved.


Anyone got any ideas? The customer is anxious to avoid getting embroiled in
a buck-passing demarcation dispute between Tiscali and BT.

Martin Underwood wrote:
> I've been investigating a very weird broadband problem for a customer.
> Anyone any ideas what could have gone wrong?
>
> The customer has an XP Home SP2 PC, connected by Speedtouch 330 modem to
> Tiscali at 2 Mbps. He can connect 100% reliably and can send/receive email.
> But most web pages are taking several minutes to display (with a blank white
> screen until they have loaded), and when they do load, any JPG images are
> missing and replaced by placeholder rectangles. Some sites such as
> news.bbc.co.uk display partially (eg just the BBC News maroon banner) and
> then complete the loading (without pictures) a few minutes later.
>
> I've turned off Windows Firewall and Norton Anti-Virus. I've installed Opera
> to eliminate problems with Internet Explorer. Apart from displaying the text
> of pages (but not the photos) instantaneously, the symptom is the same with
> 0pera.
>
> Doing a "View Source" during the "white screen" time, the HTML is truncated
> as if it hasn't completely transferred.
>
> I tried using the DOS-mode ftp to upload a variety of files (doc, pub, jpg -
> a few hundred KB) to my web server and then to download them again. All
> files go up OK and all except JPG transfer back down OK; the JPG only
> transfers about 1KB and then stops transferring without any error message.
>
> I can ping the sites OK. I can do a "telnet news.bbc.co.uk 80" and get a
> response, suggesting that port 80 traffic isn't being blocked.
>
> I've tested the PC on my DSL line, both using the customer's modem and my
> router, and everything works perfectly.
>
> I've tested my router on his line and the symptoms are as described above.
>
> So it looks as if the PC and its modem are working fine, and it's the line
> which is taking a long time to download HTML and is blocking JPG. Could
> Tiscali have applied some sort of traffic filtering or throttling?
>
>
> Tiscali got me to try a few simple tests like turning firewall and AV off,
> and configuring stating DNS server addresses instead of getting them from
> DHCP, and then decided that because the PC can connect to broadband and can
> access POP/SMTP, it must be a PC problem - even though I said that the PC
> works fine when connected to a different DSL line.
>
> Apparently it's never worked on this phone line. They had to get a new
> dedicated phone line installed a couple of months ago after the previous
> one, which is also the voice line, and which had worked perfectly up to that
> point, suddenly lost its DSL carrier one day and could not be made to work
> again. A neighbour's DSL line also failed at the same time. All that's past
> history, long before I became involved.
>
>
> Anyone got any ideas? The customer is anxious to avoid getting embroiled in
> a buck-passing demarcation dispute between Tiscali and BT.
>
>
FWIW I suspect something on the PC/Browser, although I would not
entirely discount gremlins in the network playing SB's.

Any chance you can try another PC/Laptop that you know is OK on the circuit?

At the very least this would prove/disprove the PC/Browser theory.

HTH

J

"Martin Underwood" <a@b> wrote in message
news:457483c7$0$8730$(E-Mail Removed)...

> Anyone got any ideas? The customer is anxious to avoid getting embroiled
> in a buck-passing demarcation dispute between Tiscali and BT.

Have you done a spyware check? Could be some nasties slowing him down.
Spybot Search and Destroy is a good program for weeding out spyware.

Maneate wrote in message
XpWdnRUB77pVG-(E-Mail Removed):

> Martin Underwood wrote:
>>
> FWIW I suspect something on the PC/Browser, although I would not
> entirely discount gremlins in the network playing SB's.

Even though both IE and Opera work fine on my network but fail on the
customer's?

I'd forgotten one other symptom: when I installed AdAware to check for
spyware, it wouldn't update itself with the latest definitions on the
customer's DSL line (it identified the presence of an update but then gave a
"can't connect to server" error), whereas as soon as I connected it onto my
DSL line, it worked fine. I'm not sure what protocol AdAware uses to get its
updates.

> Any chance you can try another PC/Laptop that you know is OK on the
> circuit?
> At the very least this would prove/disprove the PC/Browser theory.

If my laptop hadn't packed in (suspected IDE controller fault), I'd have
tried it connected to my router on his line.

Beck wrote in message
45749223$0$8713$(E-Mail Removed):

> "Martin Underwood" <a@b> wrote in message
> news:457483c7$0$8730$(E-Mail Removed)...
>
>> Anyone got any ideas? The customer is anxious to avoid getting
>> embroiled in a buck-passing demarcation dispute between Tiscali and
>> BT.
>
> Have you done a spyware check? Could be some nasties slowing him
> down. Spybot Search and Destroy is a good program for weeding out
> spyware.

Yes, I've scanned with AdAware. Only things found were a few tracking
cookies. Haven't checked with any other spyware programmes. There is the
possibility that there may be a virus because the Norton expired about a
month ago. A virus scan using the existing definitions didn't find any
problems. The customer wanst to wait until he's got a working intenret
connection before updating to NIS 2007 (which will need internet to get the
latets updates).

However if there's virus or spyware, why does it only affect his DSL
connection and not mine?

"Martin Underwood" <a@b> wrote in message
news:457497b7$0$8728$(E-Mail Removed)...
> Beck wrote in message
> 45749223$0$8713$(E-Mail Removed):
>
>> "Martin Underwood" <a@b> wrote in message
>> news:457483c7$0$8730$(E-Mail Removed)...
>>
>>> Anyone got any ideas? The customer is anxious to avoid getting
>>> embroiled in a buck-passing demarcation dispute between Tiscali and
>>> BT.
>>
>> Have you done a spyware check? Could be some nasties slowing him
>> down. Spybot Search and Destroy is a good program for weeding out
>> spyware.
>
> Yes, I've scanned with AdAware. Only things found were a few tracking
> cookies. Haven't checked with any other spyware programmes. There is the
> possibility that there may be a virus because the Norton expired about a
> month ago. A virus scan using the existing definitions didn't find any
> problems. The customer wanst to wait until he's got a working intenret
> connection before updating to NIS 2007 (which will need internet to get
> the latets updates).
>
> However if there's virus or spyware, why does it only affect his DSL
> connection and not mine?

Sorry I missed the bit where you checked his PC on your line. If his PC is
okay on your line then its a Tiscali issue.

> I've tested the PC on my DSL line, both using the customer's modem and my
> router, and everything works perfectly.
> I've tested my router on his line and the symptoms are as described above.

That pretty much rules out the computer being at fault then - could it
be caused by congestion ?

Does it ever improve ? (i.e. at funny times in the middle of the night
etc)

On Mon, 4 Dec 2006 20:23:33 -0000, Martin Underwood wrote:

> I've been investigating a very weird broadband problem for a customer.
> Anyone any ideas what could have gone wrong?
>
> I tried using the DOS-mode ftp to upload a variety of files (doc, pub, jpg -
> a few hundred KB) to my web server and then to download them again. All
> files go up OK and all except JPG transfer back down OK; the JPG only
> transfers about 1KB and then stops transferring without any error message.
>
This does suggest a software problem as it is hard to imagine only jpeg and
html being affected by a problem with the line/ISP. Can you try a bigger
range of file types? Maybe some plain text, binaries, video, different
picture formats and see if anything else fails (I know you've tested a few,
it would be useful to try and find another file type that fails). They may
have something in common. Try downloading via different protocols
-ftp/http/nntp. Are pictures still blocked over an encryted connection such
as SSL (try hhtps or stunnel). Is it just jpeg over hhtp not jpeg over ftp?
>
> I've tested the PC on my DSL line, both using the customer's modem and my
> router, and everything works perfectly.
>
> I've tested my router on his line and the symptoms are as described above.
>
> So it looks as if the PC and its modem are working fine, and it's the line
> which is taking a long time to download HTML and is blocking JPG. Could
> Tiscali have applied some sort of traffic filtering or throttling?
>
>
> Tiscali got me to try a few simple tests like turning firewall and AV off,
> and configuring stating DNS server addresses instead of getting them from
> DHCP, and then decided that because the PC can connect to broadband and can
> access POP/SMTP, it must be a PC problem - even though I said that the PC
> works fine when connected to a different DSL line.
>

I was thinking there was something different about your setup that could
allow the machine to work on your line but not the customers. The router
would be the obvious thing, if it was blocking a virus/trojan, etc. Did you
set it up exactly the same? Any other networking differences between the
two setups?
The only thing that I can see that is different is the ISP. You're posting
from Plusnet. I think they block some ports that are commonly used by
viruses (135, 139, 445 maybe among them, it's a while since I left
Plusnet). If there is a virus/trojan or other malware it may only affect
the computer if it gets internet access which could be blocked by the ISP.

You could try a different firewall or try blocking everything except port
80 on your router.

> Apparently it's never worked on this phone line. They had to get a new
> dedicated phone line installed a couple of months ago after the previous
> one, which is also the voice line, and which had worked perfectly up to that
> point, suddenly lost its DSL carrier one day and could not be made to work
> again. A neighbour's DSL line also failed at the same time. All that's past
> history, long before I became involved.

It's hard to see how the line could affect only two data types unless
Tiscali had screwed their traffic shaping set-up but I'd expect more
complaints if they had. I think I'm starting to repeat myself so I'll stop.
Hope I've suggested something useful.



--
Simon.

Change spam.invalid to com to reply via e-mail

Simon wrote in message
4574a86a$0$29361$(E-Mail Removed):

> On Mon, 4 Dec 2006 20:23:33 -0000, Martin Underwood wrote:
>
>> I've been investigating a very weird broadband problem for a
>> customer. Anyone any ideas what could have gone wrong?
>>
>> I tried using the DOS-mode ftp to upload a variety of files (doc,
>> pub, jpg - a few hundred KB) to my web server and then to download
>> them again. All files go up OK and all except JPG transfer back down
>> OK; the JPG only transfers about 1KB and then stops transferring
>> without any error message.
>>
> This does suggest a software problem as it is hard to imagine only
> jpeg and html being affected by a problem with the line/ISP. Can you
> try a bigger range of file types? Maybe some plain text, binaries,
> video, different picture formats and see if anything else fails (I
> know you've tested a few, it would be useful to try and find another
> file type that fails). They may have something in common. Try
> downloading via different protocols -ftp/http/nntp. Are pictures
> still blocked over an encryted connection such as SSL (try hhtps or
> stunnel). Is it just jpeg over hhtp not jpeg over ftp?

If I get access to the PC again (if the customer calls me back) I'll give it
a try.

>> I've tested the PC on my DSL line, both using the customer's modem
>> and my router, and everything works perfectly.
>>
>> I've tested my router on his line and the symptoms are as described
>> above.
>>
>> So it looks as if the PC and its modem are working fine, and it's
>> the line which is taking a long time to download HTML and is
>> blocking JPG. Could Tiscali have applied some sort of traffic
>> filtering or throttling?
>
> I was thinking there was something different about your setup that
> could allow the machine to work on your line but not the customers.
> The router would be the obvious thing, if it was blocking a
> virus/trojan, etc. Did you set it up exactly the same? Any other
> networking differences between the two setups?

Same router, same Ethernet cable, same DSL lead, same microfilter. Identical
router config apart from the username+password. Tried using my DSL lead and
microfilter on customer's account to eliminate any fault there.


> The only thing that I can see that is different is the ISP. You're
> posting from Plusnet. I think they block some ports that are commonly
> used by viruses (135, 139, 445 maybe among them, it's a while since I
> left Plusnet). If there is a virus/trojan or other malware it may
> only affect the computer if it gets internet access which could be
> blocked by the ISP.

Hmmm. Sounds plausible.

"Martin Underwood" <a@b> wrote in message
news:457483c7$0$8730$(E-Mail Removed)...

> So it looks as if the PC and its modem are working fine, and it's the line
> which is taking a long time to download HTML and is blocking JPG. Could
> Tiscali have applied some sort of traffic filtering or throttling?

I had something similar a few weeks ago, some sites were loading ok, others
wouldn't, turned out to be a dns issue, after changing dns servers,
everything has been fine since.. Might not be relevant in this case, but
worth a shot nonetheless ;-)

P.