Ive got an intermittent problem with the Internet and my laptop. I only use the laptop for surfing the Internet lightly and that's about it. Recently it's been fine when surfing for about 20 minutes then any pages I go to show a dns error and the laptop becomes nothing more than useless. Restarting it seems to solve the issue for about 20 mins then back to square 1. I've read about the dns issue regarding a site that used to redirect computers etc from this forum and have checked to see if I was effected but I'm not. I've also turned off the firewall for a bit and it still does it.

Any ideas as I'm about to throw the laptop in the bin!

Had the exact same issue for quite some time on my Dell laptop. Tried everything I could think of from drivers to specified DNS servers (non-ISP ones). This was on a BT Homehub 2.0.

Nothing worked so eventually wiped and rebuilt the thing and it has (touch wood) been perfect for the past 6 months+.

On the plus side I discovered it was NOT a hardware fault - definitely software.

Matt, this sounds as though you don't have DHCP enabled on your computer. If you don't have it enabled, every 20 minutes you will go offline as you will be losing your IP address. What OS are you using? What firewall are you using? Firewalls can sometimes block DHCP settings or interfere with your OS DHCP settings. Some firewalls let you enable DHCP within their own settings...look for that and tick the box. You should then be fine.

Just a quick edit. Matt as it's a laptop you may find it best to configure it to automatically use DHCP (when at home for example) or a static IP address if at work when no DHCP is detected by your laptop. So do the following...(this may vary slightly depending on your OS being used).

Click Start menu -> Control Panel.

Click Network Connections.

Right click Local Area Connection and select Properties.

Under General tab, scroll down until you see Internet Protocol (TCP/IP). Click on it and click Properties button.

Under General tab, select Obtain an IP address automatically. This setting is to obtain dynamic IP address if DHCP server is found in the network and almost certainly what you are using at home. Then do the following below if you are likely to be using a static IP address....

Go to Alternate Configuration tab, select User configured. Enter the static IP address of your alternate location (for example your work IP address as many use static settings). This setting is to allow TCP/IP to use static IP if a DHCP server is not found.

After getting the above steps done, if you work at home or in an office with DHCP server enabled, your laptop will use primary configuration to obtain dynamic IP automatically. Once your laptop switches to static IP network environement somewhere else, your laptop will be auto switched to alternate configuration with the static IP you have configured. Incidentally, you don't have to configure a static IP address if you don't have one that you are likely to use. Just leave that section blank.

Hope this helps Matt.

Edited 14 July, 201213 yr by Estate Man

It doesn't sound like an addressing issue, DHCP or static. The laptop is working for 20 minutes.

Could drop into a command prompt before and after the problem, run the "IPConfig /all" command and post the results.

When the problems happen, if you go into a command prompt and "ping google.co.uk" - do you get a reply.

Likewise if you "ping 173.194.78.94" do you get a reply (this is a google IP)

The above will confirm if the problem is specifically DNS resolution that's the problem. Please let me know the results.

Other Possibilities could be power management, make sure your network device is set to never go into a power saving state via device manager.

A corrupted network stack, use the MS Fixit link here to reset it: http://support.microsoft.com/kb/299357

Or malware/viruses. Make sure you've scanned your laptop with multiple AV.malware tools to double check.

Let me know if I can help with any of the above, hope you fix it!

It doesn't sound like an addressing issue, DHCP or static. The laptop is working for 20 minutes.

Could drop into a command prompt before and after the problem, run the "IPConfig /all" command and post the results.

When the problems happen, if you go into a command prompt and "ping google.co.uk" - do you get a reply.

Likewise if you "ping 173.194.78.94" do you get a reply (this is a google IP)

The above will confirm if the problem is specifically DNS resolution that's the problem. Please let me know the results.

Other Possibilities could be power management, make sure your network device is set to never go into a power saving state via device manager.

A corrupted network stack, use the MS Fixit link here to reset it: http://support.microsoft.com/kb/299357

Or malware/viruses. Make sure you've scanned your laptop with multiple AV.malware tools to double check.

Let me know if I can help with any of the above, hope you fix it!

It could be depending on the DHCP lease.

If you're having DNS issues, try another server. Either use OpenDNS (free), Google's DNS servers, or another company.

It could be depending on the DHCP lease.

If you're having DNS issues, try another server. Either use OpenDNS (free), Google's DNS servers, or another company.

if DHCP was disabled it wouldn't get released? chances are it wouldn't work at all rather than work for 20mins and then stop working? any third party security software installed?

It could be depending on the DHCP lease.

If you're having DNS issues, try another server. Either use OpenDNS (free), Google's DNS servers, or another company.

Sure, IPConfig before and after the problem will confirm if the IP has been dropped/lease has expired.

The other test, pinging by IP, circumvents any need for host name resolution, and will tell us if it's more than a DNS issue.

Let's wait for the facts and deduce it from there.

Edited 14 July, 201213 yr by corbo

if DHCP was disabled it wouldn't get released? chances are it wouldn't work at all rather than work for 20mins and then stop working? any third party security software installed?

DHCP could be working when the laptop comes on, but then not working after the lease has expired (assuming the lease is set to such a short time). Either down to the router or laptop.

Yes...I understand what you are all saying. Trust me. It's a DHCP issue. Xreyuk is correct in that if it's not enabled your laptop will boot up, connect ok and then when the lease runs out after 20mins drop the connection. Simples! I too have experienced it in the past with work laptops that I've taken out and brought home.

Quick edit again: some updates can knock out the dhcp setting in some Windows OS's. Again, not unknown.

Edited 14 July, 201213 yr by Estate Man

DHCP could be working when the laptop comes on, but then not working after the lease has expired (assuming the lease is set to such a short time). Either down to the router or laptop.

what IP address would it have if DHCP is disabled? what lease is there to expire?

By default it will connect in the normal way dynamicaly to his ISP but won't be allowed to remain connected for more than 20mins unless dhcp is enabled. The lease is for the ip address allocated to that connection.

I'm still not convinced it's DHCP, but we're just speculating until we have some basic facts. The OP hasn't stated if he's using a static or dynamic IP address.

We can't say how he will connect "by default" because we don't know the setup. The laptop will not connect dynamically to the ISP (unless it has a very old USB ADSL modem), it will sit behind a router and traverse to the internet via NAT.

Lets wait for the OP and help based on what information they can give us.

Be interested in the final diagnosis. When this occurred for me all other devices stayed connected without issue.

Changing to static IP made no odds - xbox on static was still working fine.

Worked without issue on a wired connection. Uninstalling & re-installing wireless drivers made no odds. IPv6 disabled also didn't help.

Never resolved mine until I wiped and rebuilt the OS. Will keep tabs for any solution as I still have a backup of the image whilst this issue was present.

It's a lease problems of some kind and dhcp is the usual and most obvious culprit. You can simulate it easily by switching off your own dhcp, rebooting and then watch what happens. But of course, some more information from Matt would be nice just in case of another issue. Generally there isn't though and to be honest, I can't think of anything else it can be. But I'm always open to suggestions and I'm ready to learn. But, however he connects he has to have a lease on the connection.

Edited 15 July, 201213 yr by Estate Man

1. Open up a command prompt (Start > Run > "cmd.exe" > OK).
   
2. Type in the command "ipconfig /flushdns"
   

^ might be worth a try when you hit the 20min issue. A very odd problem.

Have you tried running the windows repair tools from a build disk?

It may sound odd, but it's not uncommon. In my organisation we get it from time to time when someone takes a laptop home and it doesn't have DHCP enabled. It runs online for exactly 20 mins then there's a DNS error. We give phone support for this and just get them to tick the box for enabling DHCP and then reboot. Problem solved. It's usually a new laptop that hasn't been properly configured or it's a machine that's had massive updates and the DHCP settings have been knocked out.

We just need Matt to come back and tell us how it is now.

To me this sounds more like a virus or some bit of malware to be honest.

I can't see any home grade router having such a short DHCP lease time. Plus if the lease can't be renewed I am pretty sure the machine just keeps using the IP address.

Better questions to ask would be:

- is DHCP enabled? or is static addressing in place

- what server(s) are being used for DNS? Is it the router or are ISP / Google / OpenDNS ones being pushed out via DHCP

- when "DNS failure" occurs after 20 minutes, can you ping the default gateway (generally this is the internal IP address of your router. This can be found out from issuing the command: ipconfig at a command prompt:

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . : matthewames.co.uk

Link-local IPv6 Address . . . . . : fe80::b9fc:2971:73bc:9fa6%11

IPv4 Address. . . . . . . . . . . : 192.168.100.106

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 192.168.100.254

Edited 16 July, 201213 yr by mbames

Mbames, completely agree. When the lease expires it just requests a new one. Sounds more like virus/corrupt TCP stack.

To me this sounds more like a virus or some bit of malware to be honest.

I can't see any home grade router having such a short DHCP lease time. Plus if the lease can't be renewed I am pretty sure the machine just keeps using the IP address.

Better questions to ask would be:

- is DHCP enabled? or is static addressing in place

- what server(s) are being used for DNS? Is it the router or are ISP / Google / OpenDNS ones being pushed out via DHCP

- when "DNS failure" occurs after 20 minutes, can you ping the default gateway (generally this is the internal IP address of your router. This can be found out from issuing the command: ipconfig at a command prompt:

DHCP lease time is universally 20 mins. There are some deviations but not usually for home or most business users. However he connects to the internet makes no difference. It's his laptop that is at fault and not his router or modem. Otherwise he could not re-connect after a reboot. He would need to reboot the router each time if the DHCP in the router was not enabled and he doesn't say that he needs to do that. There is no tcp stack corruption as this would nearly always be permanant (in the general order of things I've never seen a tcp corruption that wasn't permanant until a fix is employed) and he would not be able to reconnect after a reboot. When a lease expires, the computer will not request a new one if DHCP is not enabled. I still cannot think of anything else other than DHCP as the problem on the actual laptop. It's obviously enabled on the router as he can reconnect after a reboot. So it's the LAN DHCP not enabled as far as I can see. And no, he will not be able to ping the router until after a reboot. Yes, I know he hasn't said he is connecting with a router, but nearly everyone does and if it were a modem it makes no difference anyway, and the fix would still be the same. Enable DHCP on the laptop. But, I do wish Matt would post back so we know he is ok now, or give us more info. Maybe...heaven forbid, he has lost all his internet and everything we are saying is just poo!!!

Edited 16 July, 201213 yr by Estate Man

DHCP lease time is universally 20 mins.

Really? I thought in Windows AD it was 8 days?

He would need to reboot the router each time if the DHCP in the router was not enabled and he doesn't say that he needs to do that.

If DHCP wasn't enabled in the router he would have to have a static IP address, otherwise the OS would make a DHCP request, not get a response and probably self allocate a 169.x.x.x address which would more than likely not be route-able to the internet.

I still cannot think of anything else other than DHCP as the problem on the actual laptop.

Some errors should appear in the event log in that case. Something else for Matt to look at if he resurfaces. <waves> hello Matt, are you there?!

DHCP lease time is universally 20 mins.

Sorry, what? I assure you it isn't. My work network is a day, or 86400 seconds, and I know this for a fact because it's my DHCP server.

I've read your posts in this thread, and I'm sorry to say that I don't think you know what you're talking about. Your nonsense about "if he has DHCP disabled then he can still dynamically connect to the Internet" hasn't been true since the late 90s, when ISPs still sent out modems with their connection packs and not routers (wireless or otherwise). If a client doesn't have DHCP enabled, it will never request an address, not even for the initial 20 minutes. And if it does have DHCP enabled then it would just send another request after 20 minutes and probably be re-ACKed on the same address, as a home network probably doesn't have problems with IP exhaustion causing them to be re-assigned.

gac, that's fine. My home network is 3600 seconds and work is set to 7200 seconds, although we are about to increase our computer numbers so that will change to ease the load on the network chatter. But no doubt Matt will connect up and come back to us for assessment.

Can I ask why you have such a small lease time for both your home and work networks?

So then, according to you, lease time is "universally" 20 minutes even though you yourself have two networks where that isn't the case? Everything I read just makes you look more like someone to be ignored, I'm afraid, your contradictory advice is very difficult to follow and I'm certain will turn out to be plain wrong.

gac, that's fine. My home network is 3600 seconds and work is set to 7200 seconds, although we are about to increase our computer numbers so that will change to ease the load on the network chatter. But no doubt Matt will connect up and come back to us for assessment.

W... T... F... are you talking about?

I would say the OP's original problem has bugger all to do with network settings, he more than likely has some malware.

Download, install and run malwarbytes etc and report back how you get on.