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fearlessfosdick
join:2001-08-22
Stamford, CT

fearlessfosdick

Member

Can't reach some popular sites

Hi, I have an annoying and perplexing problem. There are some web sites I can't reach or take more than five minutes to load. Most other sites work fine.

My ISP, AT&T UVerse, has been no help and I'm stuck.

Two major sites are finance.yahoo.com and att.com (YES, I can't reach my ISP!)

When I ping finance.yahoo.com I get 216.115.101.178. If I try to go to 216.115.101.178 I get a page saying "We'll be right back" I don NOT get the "normal" finance page.

When I ping att.com I get an IPV6 address: 2001:1890:1c00:3113::f:3005. That one I can't reach at all. Instead I get a google page.

I have several PC's here. They all have the same problem. Except for one PC that uses a VPN connection and thus bypasses AT&T for all practical purposes. That one PC works!

I've tried using OpenDNS as my DNS servers. It doesn't help.

I simple have no clue as to what's going on here.

Any help would be greatly appreciated.

Thanks

billaustin
they call me Mr. Bill
MVM
join:2001-10-13
North Las Vegas, NV

1 recommendation

billaustin

MVM

Log into the router and see if you can turn off all IPV6 features.

fearlessfosdick
join:2001-08-22
Stamford, CT

1 recommendation

fearlessfosdick

Member

Hi Bill,

It worked to a large extent. Now, instead of taking an inordinate amount of time the pages load in about a minute.

That's a huge improvement, but still quite frustrating.

Thanks for the idea! I appreciate it.

BTW dslreports is one more site in the doesn't work or takes too long category.
HELLFIRE
MVM
join:2009-11-25

HELLFIRE to fearlessfosdick

MVM

to fearlessfosdick
said by fearlessfosdick:

There are some web sites I can't reach or take more than five minutes to load.

said by fearlessfosdick:

My ISP, AT&T UVerse,

DSL service + slow / noload pages... first thing I'd check is for any MTU issues.
Best way to test for this is ping a page that's taking long to load; in Windows

ping [ip address] -f -l 1500
 

which says send to [ip address] 1500byte ping packets with the Don't Fragment bit set.
If it comes back with "Packet needs to be fragmented but DF bit set," you know that's
too big an MTU, so decrease the packetsize accordingly till you get successful pings.

Once you find a packetsize it can send through, check your DSL config if the MTU size
matches this or not.

My 00000010bits

Regards

shdesigns
Powered By Infinite Improbabilty Drive
Premium Member
join:2000-12-01
Stone Mountain, GA

shdesigns

Premium Member

Should be:

ping [ip addr] -f -l 1472

for 1500 bytes due to 28 byte overhead of packet.
hardly
Premium Member
join:2004-02-10
USA

hardly

Premium Member

Is it -l or -1

billaustin
they call me Mr. Bill
MVM
join:2001-10-13
North Las Vegas, NV

billaustin

MVM

lowercase L

fearlessfosdick
join:2001-08-22
Stamford, CT

fearlessfosdick

Member

Thank you guys so much for the info. I tried your suggestion using both

ping 144.160.155.43 -f -l 1472 and
ping 144.160.155.43 -f -l 1500

The first went through with no problem but the second ( -f -l 1500) resulted in "Packet needs to be fragmented but DF set.".

So do I need to lower the MTU or not? would an MTU of 1472 be sufficient? And what does "but DF set" mean?

Thanks again,

FF
HELLFIRE
MVM
join:2009-11-25

HELLFIRE to fearlessfosdick

MVM

to fearlessfosdick
said by fearlessfosdick:

So do I need to lower the MTU or not? would an MTU of 1472 be sufficient?

This test ONLY tells you that you can move a packet with a MTU of 1472 bytes to 144.160.155.43. Why I'm suggesting
to go up to a value higher than 1472 but lower than 1500 is to find out exact WHAT that maximum is. THEN once you've got
that, you'll need to check whatever is between your computer and phone line / AT&T service -- guessing you have an
all-in-one jobbie from AT&T that gives you wired/wireless connectivity and DHCP service, yes? -- to make sure it's set
to whatever value you find. If it isn't, then you'll need to reconfigure it.

Also you mentioned there were other websites, so you'll have to perform this test on all of them to make sure -- maybe
one website has a max MTU of 1472, and another has 1359, for example... you never know.
said by fearlessfosdick:

And what does "but DF set" mean?

»en.wikipedia.org/wiki/IP ··· entation -- to understand what fragmentation is, first of all.
Setting the DF bit basically tells whatever devices your packet hits to NOT break it into smaller fragments.

My 00000010bits

Regards

fearlessfosdick
join:2001-08-22
Stamford, CT

1 recommendation

fearlessfosdick

Member

Well I tried MTU = 1472 and even MTU = 1042.

Neither seemed to make much difference compared to MTU = 1500.

So I went back to 1500 at least for now.

The major improvement seems to be due to billaustin's suggestion to disable IPv6.

Most of those sites I'm having problems with now seem to load in about a minute or less. That's still annoying but much better than b4.

As I said above, the MTU setting doesn't seem to make a difference.

Anything else you can think of?

Many thanks,

FF
fearlessfosdick

1 recommendation

fearlessfosdick to HELLFIRE

Member

to HELLFIRE
Hi,

I'm astonished that the problem has completely disappeared!

NOTHING here has changed other than the disabling of IPv6 which I did a couple of days ago. The MTU is still at 1500.

The only explanation I have is that AT&T actually found and fixed the problem. I had previously said that tech support was clueless about the issue; but I know they were interested because att.com was one of the problem sites. So perhaps someone higher up found and fixed the problem.

Thanks to all for your help and suggestions!

FF
HELLFIRE
MVM
join:2009-11-25

1 recommendation

HELLFIRE to fearlessfosdick

MVM

to fearlessfosdick
said by fearlessfosdick:

Anything else you can think of?

Something like HTTPWatch to check what object(s) a page is loading, and what (if anything) is holding it up.
Find someone else on AT&T uverse in your neighborhood and see if they have the same problem or not.

I always welcome good news that things are working again, tho...

My 00000010bits

Regards