Strange DNS resolution problems with new provider

Having recently transferred from my hellish previous DSL provider, I'm now ensconced with O2, and after the customary week of broken assurnaces, hassle and billing mistakes I finally have a connection that, in general, seems to be working well. However I do now have an odd issue with DNS resolution that seems to be a problem at my end (either with the computer or the router), rather than with the line. Apologies if this is in the wrong forum for a query like this; I wasn't quite sure where else to put it.

I'm using the standard O2 router (using ethernet, not wireless), which they call a "wireless box II" (I believe it's a branded Thomson of some kind). My system is a laptop running XP SP2.

Basically, on some occasions most or all resolution of domain names seems to become impossible, and fails in pretty much all cases (though see below on pings). This problem seems to arise when the computer goes into sleep mode, or the connection is disabled and then re-enabled in Windows, or if the connection between the computer and the router is in any way interrupted by whatever other means. When it reestablishes itself, DNS resolution in all web browsers, email clients, and other applications fails. Connections to known IP addresses are absolutely unaffected and work fine in all cases.

What is particularly bizarre is that the nature of the problem varies - in some cases of this problem, I can ping URLs from the command line successfully, but all other applications that need to resolve them (web browsers, email clients, etc) fail to do so. At other times, pings to URLs also fail along with everything else. This doesn't seem particularly predictable. What is also interesting is that while the pseudo-domain name that can be used to access the router's configuration (http://O2wirelessbox.lan) does not work when this problem arises, typing in the router's IP address on the local network does work. I assume this means the problem lies somewhere between my system and the router, rather than with the external line, or the ISP's DNS servers.

A full reboot of the computer, leaving the router active during it, resolves the problem in all cases. But this is time consuming, and isn't really acceptable in the long term as I move my laptop about a lot. Rebooting the router with the computer left on never solves the problem.

I never had this problem with my previous provider (who provided rubbish USB-only hardware that I couldn't afford to replace, so I don't have any previous experience of using an ethernet-based connection to a router).

I was wondering if anyone might have any idea what the problem could be, and how it might be resolved. Many thanks in advance.

Zaarin.

Be / O2 have a history of DNS problems. You could use OpenDNS instead or look in the Be or O2 forums for specific advice.

As you say this doesn't seem to be an ISP DNS issue because rebooting fixes it.

In the past I had similar issues resuming from hibernate using a WiFi link which I had allowed to use DHCP. I resolved it by hard coding the IP and DNS addresses in the adaptor properties. I have alway done this with my wired connections anyway and have never had a problem with those.

I think it must be caused by the DHCP lease expiring and it may be possible to fix it by "telling" the router to always allocate the same IP address but it's probably easier just to hard code it on the PC. If you can't figure out how to do this or what addresses to use ask again - typically you'd pick an IP something like 192.168.1.100 with a subnet mask of 255.255.255.0 for the dns either use whatever you see in use when you type ipconfig /all in a command box or specify the opendns ones (in case Be do screw up) - www.opendns.org - I think there are examples on the site how to set these up and the IP address is done in the same way.

We had the same or worse with my son's PC and XP (SP1 and SP2). Basically XP's wireless is designed to hunt - its like they wrote it for roaming within a large office site where you'd want it to find the nearest/strongest node as you moved about.

Anyway - if you get a poor link to the router or suffer sporadic radio noise then XP goes mental trying to fix things for you. Naturally it messes things up.

DHCP - It was especially good at missing DHCP by looking while the card was reestablishing the link so its well worth hard setting the IP, etc for the interface.

NB: XP and its drivers also have an emergency backup IP that they issue if there is no DHCP server. It was designed for zero configuration environments, think Joe User with two PCs and a networked printer. As far as I know its hardly documented and no-one ever uses it - But - its there to mess things up. This can also be avoided by hard setting the IP, etc.

There is also an option to configure a fallback IP, etc which is used if DHCP fails. We tried setting this also - results were less conclusive.

You can spot the DHCP issues by doing an ipconfig in a command prompt. After the link is lost you get given a new IP which is in one of the private (unrouted) ranges. Like 192.168 but a different one.

After this the roaming emphasis in the XP/WLAN drivers will also try to mess with you. If the link is still poor at the moment XP deems to reconnect it will not find/accept your router. At this point it is prone to conecting to ANY other WLAN out there. It may be the strongest or it may be the first or last. We were never quite sure. It may even be the first insecure WLAN.
Anyway having connected to this and usually being rejected (as its not even using your WEP or WPA key) you are left with an unusable but connected connection. So there are no reconnection attempts. Sigh. The roaming is extra messy if you have the IP settings hard coded as its uncertain they will even be compatible with the subnet you have connected to.

We tried all this with several versions of drivers, two different WLAN cards, differently branded drivers (to get later versions) and using both native drivers and the horiffic Windows Zero Configuration. Oh and I checked the router's internal aerial connection and moved it to the RouterTech firmware (highly recommended) which was infinitely better in everything else but produced no improvement in the wireless. We eventually lifted some carpets & floorboards and ran a wired connection!

Its possible that the problem appeared when our house wiring/earth was improved and was precipitated by more noise or more earthed cable in the radio path. Or maybe more neighbours got wireless. The machine was also upgraded from win98se to winXP about the same time so its hard to pin down the cause. And before anyone says "Ha, Router!" I'm connected to that from another room with no problem (from a 98SE laptop) and my daughter's room is also fine (on ME - don't ask) using one of the cards we'd had in my son's XP...!?!?

Curiously 98SE on that PC does not produce the same extreme problems and even if the link is lost it recovers gracefully whereas XP's support seems designed to fail horribly in any unstable environment.

Not sure why the situation should have changed with a change of ISP ?
but problems with internet access via wireless network not working after resuming from Sleep/Standby seem not unusual in some laptops and I couldnt find a fix when I had this problem - just started using hibernate instead.

this sounds like a power management issue, especially as it only happens after the pc has gone into sleep mode, if you go into device manager and right click on your ethernet adapter,click on properties, and there should be a power management tab with various options.i.e allow the computer to turn off this device to save power and allow this device to bring computer out of standby. enable these and see if it does the trick.
hope this helps

Hi everyone, many thanks for the helpful replies. I think setting a static IP on the local network may have solved the problem, but I can't be sure until I've tested it for a day or two.

> Not sure why the situation should have changed with a change of ISP ?

I suspect it is not unrelated to the fact that Be supply a router. It's the change of router behaviour that has caused this issue not the change of ISP.

My betting is that it will have fixed the problem for you just as it did for me.

I have found over the years that if there is a choice of letting MS software configure something for you or doing the job manually then the latter course is more likely to work consistently.

Details here:

http://www.adsl2forum.co.uk/showthread.php?t=9145