Windows 7 Repeatedly Loses Network Connection in Weird Way

[The Gorn]

Ever since I built this box, one nagging problem has persisted. Here's how it unfolds.

1) After having worked OK for awhile (hours maybe) with internet access, the network indicator in the task bar status area displays either a swirling aqua circle or the yellow triangle with a ! in it.

2) No internet sites are accessible, email doesn't work. I get "site not found".

3) I can, however, point a browser directly (via 192.168.0.1) at the built-in web server in the router - a DLink DIR-655 -  and get the login screen and view the network status (showing that the internet is "up".

4) An ipconfig command will show the garbage default address 192.168.56.1.

5) After some time (a couple of minutes or so) the network status indicator will revert to working (no yellow triangle with a !) and all is well at the browser end, etc.

I have experimented with a few fixes. The network card and the router are both 1 GB and I had the network card set to auto-negotiate - the network adapter status showed that it had achieved 1 GB. I changed the settings to make it 100 MB fixed. Also, I read on a forum that disabling IPV6 support would help. Neither makes any difference.

Sometimes this problem manifests itself at boot up - the network adapter will simply not show "enabled" for several minutes after the system has stabilized at startup.

Any thoughts?

[I D Shukhov]

I have 2 HP computers that both use Windows 7 and the same Actiontec GigE router.  The older one has a NVIDIA nForce 10/100 mps network adapter and the other one has a Realtek PCIe GBE adapter.

With the first one, about 20% of the time a connection is not established.  I then right click on the network connection icon in the toolbar -> troubleshoot -> troubleshoot as administer and it always fixes the problem.   I've not been motivated enough to try to figure out what the problem is.

The newer computer has never had a problem establishing a connection.

Windows just found an updated driver for the NVIDIA nForce controller which I downloaded and installed.  This may be promising.  I have A/B switchboxes between my computer and the router.  On the older PC, the failure scenario usually is that I switch the A/B box on and then log on.  I just tried this a couple of times without a failure.

[DG9]

I have a similar issue with my DIR-615.

I then right click on the network connection icon in the toolbar -> troubleshoot -> troubleshoot as administer and it always fixes the problem.   I've not been motivated enough to try to figure out what the problem is.

Sometimes everything is smooth for weeks, then periodically I have to use the technique mentioned above repeatedly.  Does powering the router off/on and/or rebooting clear it up?

[pxsant]

This really does sound like a network driver problem as I.D mentioned.  What is the chipset on the network adapter?  I would search for a new adapter driver on the Internet to see if there is a later driver.

As an alternative, you could buy a plug in network adapter with a different chipset to see if you can solve the problem.  They are pretty cheap so it is an inexpensive test.

[The Gorn]

I didn't mention: when this happens the "Troubleshoot problems" context menu command doesn't do anything. It just terminates after a few seconds of running and says it can't fix the problem.

I just saw an optional update of the driver for this box (Realtek) in the updates list and I just took it. I was afraid to - I almost bricked my laptop a few months ago by taking an updated video driver.

[benali72]

I'd try Linux to see if you still get this behavior, if not, you can be sure it's a software problem.

My guess is that it is a driver problem. As far as updating the driver goes, I don't have Win 7, but isn't it true you can roll back any driver you apply? If so it shouldn't be too big a risk to try a new/updated driver then roll it back if necessary.

[The Gorn]

I dunno, this does not smell and feel like a network driver issue.

When it happens, public internet access goes away and remote sites become unreachable, BUT I can still access the router's local config menu from that PC using a direct IP address. It seems to me that if it were a driver (pseudo network card hardware) level issue, all network access would be kaput.

No other PC on the network (my wife's computer, a laptop) using the same router has a problem with getting out to the internet or sees the connection drop.

I personally think it's some misconfigured or conflicting application or service setup in Windows 7. But inspection of the various system logs after this happens does not show anything happening right at that moment.

[Walter Mitty]

As long as we're down to what it smells and feels like, I'll tell you my first guess:  it's a DNS server problem.  I wanted to avoid guesswork until somebody who knows the answer had a chance to respond.

[DarkHumour]

Is it double natting ? 

Sometimes you can get away with this for a while and most customers set up their gear that way until I intervene.  Now that ISP provide a combo router modem it occurs more frequently.

Quicky example
(internet public address <-> isp cable/dsl box <-- (private address 192.x.y.z) -> (assigment 192.x.y.1 'wan') -> router (assignment 192.a.b.1 'lan' )

Also Comcast has 'secured' DNS servers now 75.75.75.75 and 75.75.76.76.  I usually set the gateway and the dns the same on my router box unless I have a server running dns internally. (Or set it as an alternate failover DNS when the server craps out).

DarkHumour

[The Gorn]

No double natting here. The D-Link router accepts the direct public IP address on the WAN side and on the private internal side dispenses 192.168.bla.bla addresses.

I just had it happen again today. The network card in the PC apparently did not even get an address assignment, because I could not even go to the private web config screen in the router.

[PhilFromNY]

I've had it in the past that when a dynamic IP address cannot be renewed the system winds up with a garbage one. A couple of thoughts:

Have you tried a static IP address?

Does the DHCP lease length match the frequency of your problem?

Have you tried manually renewing your IP address? (In a command window ipconfig /release and then ipconfig /renew)

[The Gorn]

I've had it in the past that when a dynamic IP address cannot be renewed the system winds up with a garbage one. A couple of thoughts:

Have you tried a static IP address?

Does the DHCP lease length match the frequency of your problem?

Have you tried manually renewing your IP address? (In a command window ipconfig /release and then ipconfig /renew)

These are good ideas. I'll check out the DHCP lease length.

Right now I am using a feature of the D-Link router that assigns a fixed address (via DHCP) to every computer, as identified by each computer's MAC address. I could just hotwire the afflicted computer to be fixed at the same address and see if that fixes anything.

[I D Shukhov]

What about a thermal problem?  If it works for a while, stops and then starts working again maybe there's a flaky transistor in the network card? 

[DarkHumour]

What about a thermal problem?  If it works for a while, stops and then starts working again maybe there's a flaky transistor in the network card?

Or the dreaded 'blown cap' on any of the hardware... although that has mostly been shaken out of the industry.  That Mac address to IP -lock feature/method is how I try to do DCHP in small environments so that there is no client configuration needed on the workstations, all the work is done on the server...sort of a pseudo fixed IP address.  This is good for having to do direct remote and port forwarding.

I think IPV6 was already mentioned as a culprit of issues.  In the past I had problems with Intel 1000MT NICs because my cable was "too short" which was bizarre.  Maybe there is a newer driver for your card directly from the manufacturer  and/or firmware for your router.

DarkHumour

[Richardk]

Aside from a hardware failure, I'm leaning towards the lease time as well.

The DHCP Reservation process still requires your computer to request an IP address but it 'looks' like a static IP from the outside. I guess another option is to make it static and see what happens.