Windows 7 - No internet access

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Mind Scar

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Hi all, I am new to this forum.

I'm experiencing this really weird problem. The company I work for has 3 different sites. The head office here in Durban, one in JHB and one in Richards Bay.

All these sites are linked via vpn over a l2tp tunnel using strattice wipod routers. About a month ago our Richards Bay branch had moved to a new premises so I moved the network over respectively. After the move, every windows 7 (3 of them) display "no internet access" with a yellow exclamation triangle over the network status symbol. These computers periodically will connect to the internet then disconnect in an interval of about 30 mins. They can see the internal network but not the internet. The other PC's, the windows xp ones don't suffer from this problem.

The setup is exactly the same as it was before in terms of network infrastructure. I have tried various solutions from the internet like reseting tcp/ip stack, winsock reset, assigning static ip address, updating network drivers, disabling ipv6 etc

It's been going on for a month and I'm wondering if anybody else here has had this problem or has a solution.

Many Thanks
 
I think I may have stumbled across something like this before with Windows 7.

Open Network and Sharing Center, and under the View your active networks section, make sure it says Work Network, and not Public/Private/Unknown. This is known as your Network Location, and is something new in Windows 7, that wasn't there before in Windows XP. There are different firewall/security rules depending on what your network location is set to.

The network location can sometimes change, especially if you change the DHCP server, or a switch, or change things around in your network (even the order of connections). Once you choose a network location, I think Windows remembers the MAC address of the first device it connects to (like a switch, router, DHCP server) and associates with that location. The next time you connect to a network, Windows will compare the MAC addresses it has stored on file, with the first MAC address it encounters. If it finds one that matches, it knows on which network you are, and will set the security rules. If it doesn't, it will assign you to a new Unidentified network that is either public/private/something which has different security rules.

The above is not verified info, but from the top of my head of what I could piece together. I'm sure if you Google "Windows 7 Network Location" and other related terms, you'll find the correct official info/explanation.

I believe the Network Location is meant to be more useful to mobile devices (laptops, netbooks, etc) that are mobile, and connect to many different networks (work, home, coffee shop, airport, friend, etc), and have different security settings for each network.
 
OK.. managed to find some links:

http://windows.microsoft.com/en-US/windows7/Choosing-a-network-location
http://www.sevenforums.com/tutorials/71408-unidentified-networks-set-private-public.html
Not completely related, but useful - http://www.sevenforums.com/tutorials/24683-network-name-icon-change.html

Google a bit more and you will find a better explanation. My guess is that Windows 7 remembers certain MAC addresses on a network in order to identify it in case it encounters the same network in the future.
 
Best explanation I could find: http://superuser.com/questions/3735...ied-what-requirements-must-the-interface-meet

Read through all the answers, particularly this one:
Networks are identified according to the MAC address of the router. So if you have no gateway defined, this causes a problem. You need a gateway address to be set in your TCP/IP settings, or if you are getting these by DHCP ("Automatic") then you need to make sure the DHCP server is giving out the correct gateway IP.

Note: if you are on a wireless network, your network location has nothing to do with the SSID (network name) or the IP or MAC of the access point, but of the router. In an integrated wireless/wired/router device, this may have several MAC addresses for the different interfaces, but should tell Windows the right one for the router, so you can connect through wired or wireless and have it recognise that you are on the same network.
Click to expand...

It seems the MAC address of your router (ADSL modem / WAN router / firewall device / default gateway) has changed. This is probably because it has several ethernet ports on the router, each with it's own MAC address, and when you reconnected your network, you didn't reconnect the router to the main switch using the exact same ethernet port on the router. Hence you changed the MAC address of the router, and Windows could no longer identify it, and used a default "safe" network location. Hope this helps.

Let me know how you resolve the problem.
 
Thanks. I already tried changing the network location to work. I reloaded one of the win 7 laptops and sent it back today, seems to be working. I think your info on connecting the router on a different network port is correct and this may be the cause but now I need to find a way to get the other Pc's to see this new Mac address for the new port on the router. The branch is 200 km away from me and I support it remotely and telephonically so trying out each port on the router will mean me driving there, i will if I can't find a solution. Thanks a mil for your help bud, I hope I can find a work around for this.
 
I've had this on a 'new' Windows 7 - never seen the network before.
A XP machine worked fine.
Point is, the LAN/MAC settings has nothing to with it.
If I remember correctly I set the IP manually and it worked.

BTW this setup was on a farm behind a Mikrotik wireless router & link.

I haven't been able to find out what makes the exclamation come or go. Does it ping a specific site or what?- maybe the windows update server?
 
I tried resetting in the TCP/IP stack and Winsock reset. They both don't work.

I've also tried setting up static addresses, still no luck. The pc's do obtain the correct IP settings from the dhcp server. I can ping everything on
the internal network, nothing outside (except when it does periodically connect)

I still think you are right about the change in plugging in the router on a different lan port. I'm going to get somebody there to plug it into each port to see if the problem goes away, will let you know how this goes tomorrow.
 
From what I've read the NCSI service performs a DNS lookup on www.msftncsi.com, then requests http://www.msftncsi.com/ncsi.txt.

NCSI then sends a DNS lookup request for dns.msftncsi.com. This DNS address should resolve to some 130 IP address. If this succeeds then it will display internet access if not the it does the opposite.

I've tried every internet solution I could find, if I Google this, all the links show up in purple!
 
After much reading I have finally found the solution to this problem.

Here's how I have solved this problem.

First, I used the "arp-a" command to view the arp entries. The Ip address of the default gateway wasn't corresponding to the mac address of the router so I then used "arp-d ip address" to delete the entry. If I added the arp entry for the router dynamically it used to work for a while then drop the connection again. I then added it as a static arp entry and all is working well. Using the "arp -s" was unable to add the static entry. For some odd reason it kept on coming up with "access denied" even though I was running command prompt as administrator so I used these commands instead.

netsh interface ip delete neighbors "Network interface name" Gateway IP address - To delete the entry

Then

netsh interface ip add neighbors "Network interface name" Gateway IP Address Mac Address - To add the static entry

You can get the names of the valid network interfaces by using

netsh interface show interface

In my case it was called local area connection

Thanks to Saajid for pointing me in the right direction
 
Awesome. Glad you managed to find a solution, though I'm still not convinced that the above is the "right" way of doing it. There should be no need to add static ARP entries on each machine. Seems like a temporary solution...

Crux of the matter is that ou need to figure out why the "Ip address of the default gateway wasn't corresponding to the mac address of the router". I assume that the ARP table on each Windows 7 box was reflecting this same incorrect info?

Are your Windows 7 machines running the latest service pack and patches? Perhaps there is a bug in the Windows 7 network stack that doesn't deal with stale ARP entries effectively, and this issue was fixed in later Windows Updates. Why I suspect this is because when you reinstalled Windows on one of the other machines, the problem disappeared. Perhaps you installed a different version of Windows 7 (e.g. Windows 7 + SP1) or you first updated to include all the latest patches and fixes.

Also, perhaps try upgrading the firmware on the router - it could have a bug that only manifests itself on Windows 7 machines.
 
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