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What are some of those other programs that let you override the MTU settings, as I'd rather not go into the registry myself as the Microsoft article describes?  They have a Netgear router.  I don't know what MS Internet Connection Sharing from one PC is, but from the sound of it, it sounds like its a software component that does something similar to the router.  So I would guess they're not using it.  If it helps, there is only one item in the Network connections control panel and that's the Ethernet card.  I read the Microsoft article lrmoore linked above, but what I don't understand is why this problem still persists even though we have downloaded and installed Service Pack 1 for XP, which the documentation says should fix the problem.  Any more hints?

I have some updated information on this.  I tried what the Microsoft article suggested about ping -r? -l (can't remember syntax off hand) and then the MTU to the default gateway, which in this case is the DSL modem.  As you'll predicted, it came back fragmented.  I kept lowering the MTU and pingin until I got to 1472 and then it came back "reply" instead of fragmented.  So, I used the DrTCP utility to change the MTU to 1472.  I then rebooted the computer and expected to be able to browse.  I went to Jigzone.com, which is one of the sites the client wanted to browse and it still didn't work.  So, I thought maybe the utility didn't work, so I followed the Microsoft instructions and found the registry key for MTU value and sure enough it was set to 1472.  So, I'm scratching my head and then I thought, well let's ping it again at 1472 and see what happens.  This time 1472 comes back fragmented.  So I kept pinging until I found another number that sent "reply" back, set the MTU to that number, and rebooted.  Same thing. Wouldn't connect.  So, I tried the ping again and this time it was down to 1430.  It was as if everytime I rebooted the computer the MTU went down.  Since it was a viscious cycle, I stopped.  I did some further research on this and read a suggestion to configure the router instead of the MTU in Windows XP.  I put in the address of the default gateway in IE and it wouldn't come up--page not found.  So, I went to look at the equipment and discovered that they had an old NetFlx modem with one output and an old 4-port double speed network HUB, not router.  Does this have something to do with the problem? Do they need a router?  They are using static IP addresses and when you change it to dynamic IP addressing and do ipconfig /renew it just freezes.  I didn't know anything about MTUs before I started this, but after having read the documentation, I thought this was fairly straightforward and told the lady that we could probably easily fix the problem--and then this happened.  So what do I do now?  If you think the router is the issue, I can unplug mine and take it to their house as a test.  Or is it the modem or something else, like software related items?  Please help.

Hi TomAsimos,

try connecting the computer directly to the dsl modem eliminating the hub. Who is the ISP in this? If AOL I would recommend the broadband blaster modem, if SNET the Speedstream is the only one SNET will support. Set up a PPOE network connection with their login info and then check ping. the hub shouldnt be doing any harm, but eliminating it will help isolate the problem. If connect well with tehir existing modem see if you can setup internet connection sharing. get them to spring for a netgear router if thats not doable. Its a bit less troublesome then linksys. 1492 should be the ideal setting for either of the 2, but your modem is a likely culprit.


John

I can't connect the modem to the computer directly because they are in different rooms.  I can try taking my Netgear router up there and see if it works.  There is no Linksys involved.  But you think we should call SBC and get a new modem?

The problem is not resolved, but I too believe it to be a hardware problem with the modem or the line coming into the house.  What's weird is that I took my extra DSL modem to hook up and try but their DSL is not coming over the phone line.  Their modem is so old that it uses an Ethernet connection for both the network wiring and for the line port.  The customer told me that since they were one of the first to get DSL (he works for SBC) that they came in and put a spliiter outside and then ran the wire into the house.  So, there was nothing I could do except call technical support.  They verified that this particular modem had been used a LONG time ago and in very few houses.  But the DSL department said that they didn't even handle the support for it.  They said that the "line department" would have to handle it and were supposed to call the client yesterday.  I haven't heard back from her yet.  I suspect that they are just going to reprovision the line so that it is compatible with today's modems becuase it is doubtlful that they even have any of those modems to replace their current one.

Hello TomAsimos,

I just wanted to add that in my experience this problem has always been solved by Matching the MTU of the "clients" with the MTU of the "host" ( computer directly connected to the DSL modem). So far the magic number seems to be 1454 for a PPPoe setup.
 I used to do all the registry changes by hand, now you can just download the TCP optimizer from speedguide. It's so much easier to backup current settings and then tweak as needed. It also allows you to choose the exact network adapter to apply the changes to without affecting any others you may have installed.

I know you have tried changing the mtu to resolve this but it's very possible that you didn't match any of the machines mtu and that you may have changed the mtu for the wrong adapter in one or more of the machines, especially if you have a mixed OS network.

Just my two cents, you can use the link below to download the tcpoptimizer.

http://www.speedguide.net/files/TCPOptimizer.exe

-Gordon