Win 7 Losing Network Intermittently (Internet OK)

mr_zen256

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This has me stumped. We have a workstation that keeps losing network access intermittently, seemingly at random periods during the day. Restarting the PC temporarily fixes this, as does disabling and enabling the network adapter. The following is a list of things already tried to fix the issue:

  • Deleted/Re-entered network credentials (Enterprise)
  • Changed network cables
  • Updated NIC drivers
  • Changed Static IP address
  • Changed NIC Power management options to always on
  • Updated registry auto-disconnect range
  • Replaced NIC with new PCI-e NIC
  • Enabled NetBIOS in Adapter properties
  • Enabled Computer Browser service in "Services.msc"
  • Enabled TCP/IP NetBIOS in "Services.msc"
  • Changed mapped drive to network share
  • Changed mapped drive by name to IP address
  • Changed cables for second time to make sure (including network wall jack)
Any ideas?
 
Last edited:

JBark

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Onboard NIC? Could also try updating the BIOS or checking for ethernet power saving settings in the BIOS.

Though I've seen something like this before with a PC here at work, and I'm 99% sure I was just seeing the death throes of the onboard NIC, since I never did get it working consistently. I just disabled it in the BIOS and plugged in a PCI NIC, and it was fine after that.
 

mr_zen256

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Onboard NIC? Could also try updating the BIOS or checking for ethernet power saving settings in the BIOS.

Though I've seen something like this before with a PC here at work, and I'm 99% sure I was just seeing the death throes of the onboard NIC, since I never did get it working consistently. I just disabled it in the BIOS and plugged in a PCI NIC, and it was fine after that.

Yeah, onboard. I think we have a spare crappy fast ethernet PCI NIC laying around somewhere I can use for testing.

I'll take a look at the bios before switching. It's shocking how often these onboard NIC's fail.

Thanks for the suggestion!
 

mr_zen256

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Am still entirely baffled by this workstation STILL losing it's network connection. I have tried everything I can possibly think of to get this solved (list in original post). The only thing I can think of is to do a re-install of Windows, but I'd like to avoid that if at all possible.

This workstation did have another user that has now left the company, I'm just wondering if somehow the credentials of the previous user is conflicting. I cannot see how this might be since I have removed old credentials and updated with the new credentials on the server and User Accounts. (Entirely removed and reentered a couple of times to make sure).

Would really appreciate any final suggestions before nuking it :)
 

Quartz-1

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One thing that leapt out at me was that you are using static IP addresses. How big is the network to which the PC is attached? Can you try using a DHCP address?
 

mr_zen256

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One thing that leapt out at me was that you are using static IP addresses. How big is the network to which the PC is attached? Can you try using a DHCP address?

We have a total of 15 permanent devices. I keep a record of all workstation and device IP tables and I can confirm 100% there are no IP conflicts. I'll test out this particular workstation with DHCP though. The user arrives later than everyone else so shouldn't steal anyone elses IP :p

I have tried switching this particular workstation to a few alternative Static IPs previously and it did not resolve the aforementioned issue.
 

jpochedl

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What type of switch is the PC connected to? If it's a managed switch, do you see any errors on the interface? What's the port status when the PC appears offline?

Are you losing link (layer 2) when the NIC appears offline? (even if you don't have a managed switch, you can usually look at the switch's link status lights to see this...)
 

mr_zen256

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What type of switch is the PC connected to? If it's a managed switch, do you see any errors on the interface? What's the port status when the PC appears offline?

Are you losing link (layer 2) when the NIC appears offline? (even if you don't have a managed switch, you can usually look at the switch's link status lights to see this...)

We are currently using an unmanaged Netgear JGS524 24-port Gigabit switch. As far as I am aware, activity on both the switch port and the NIC port appears active and operating as normal when network connection loss occurs. I will double check this again when the connection drops next.

I have changed the IP of the workstation to obtain automatically via DHCP as suggested by Quartz-1 and am waiting for the user to report if the issue occurs again.
 

mr_zen256

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Ok, the network dropped out again even after changing to DHCP.

Checking the status lights on the switch, they were still active and the light was green indicating gigabit connectivity. Internet access fine, network shares inaccessible as usual.

I've never heard of a switch port being faulty but I've changed the cable to a different port, just in case.
Is there any network diagnostic software that could help diagnose the issue? I'm totally perplexed :confused:
 

systemx

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Can you make sure that the workstation is free of viruses? (give it one quick scan with malwarebytes)
If that doesn't work, please DISABLE your current antivirus solution and test again; report back.
 

d2thez

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I would your disable TCP Autotuning and if that doesnt work, try disabling TCP Chimney Offload.
 

mr_zen256

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Since the last update, the network has dropped out again after the switch port change.

Looking at the network in explorer, it appears all network devices disappear from the list under network on the left except one other machine (always the same machine). The one listed machine is not accessible. There is definitely no IP conflict between these two machines. Both machines are running Windows 7 Home Premium 64bit.

The network can sometimes restore the network connections without a reboot or restart of the network adapter.

Can you make sure that the workstation is free of viruses? (give it one quick scan with malwarebytes)
If that doesn't work, please DISABLE your current antivirus solution and test again; report back.

Clean as a whistle with Malwarebytes and MSE scans. Have disabled MSE even though we have several machines with the same configuration without issues.

I would your disable TCP Autotuning and if that doesnt work, try disabling TCP Chimney Offload.

Have disabled TCP Autotuning and waiting for problem to arise again.
 

jpochedl

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Ok, the network dropped out again even after changing to DHCP.

Checking the status lights on the switch, they were still active and the light was green indicating gigabit connectivity. internet access fine, network shares inaccessible as usual.

Whoa, wait a sec... "Internet access is fine" ? Sooo, during this network outage you can still access the internet from the affected machine? Or am I misunderstanding the statement?

During the problem, are you able to ping the machine's loopback address (127.0.0.1) ... Are you able to ping the machine's IP address from itself? Are you able to ping other devices on the network, both by name and IP address? Are you able to ping the default gateway? If no, at any point, what point....?
 

mr_zen256

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Whoa, wait a sec... "Internet access is fine" ? Sooo, during this network outage you can still access the internet from the affected machine? Or am I misunderstanding the statement?

During the problem, are you able to ping the machine's loopback address (127.0.0.1) ... Are you able to ping the machine's IP address from itself? Are you able to ping other devices on the network, both by name and IP address? Are you able to ping the default gateway? If no, at any point, what point....?

You are understanding the statement, yes. Internet access does not go down when network shares are lost. When the share is lost I can still get a ping response from the IP address of the lost network share in command prompt. I have not tried pinging the local machine when the share is lost, I will check that tomorrow when back in the office. I will also ping the gateway.
 

jpochedl

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Not to belabor the point, but still being able to access the Internet and ping devices on the network is really a key piece of information. It means that your "network" connection isn't down, and that everyone here has been trying to help you solve the wrong issue.

So, to clarify the issue... The problem is that you're losing access to SMB mapped network shares? What's hosting the share? WIndows Server 2003/2008/2012 or Linux? What happens when you try to access the share on the affected client through Windows Explorer by name (instead of using the mapped drive). Use the syntax \\servername\sharename in the Explorer address bar, or through Start > Run

Are there any errors in the Windows client's event logs?
 

Quartz-1

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Not to belabor the point, but still being able to access the Internet and ping devices on the network is really a key piece of information. It means that your "network" connection isn't down, and that everyone here has been trying to help you solve the wrong issue.

Agreed. Is the user getting temporarily locked out? Perhaps there's an application with a stored old password. Are you able to ping the server by name as well as IP address?

What happens when someone else uses that machine?

BTW top tip for managing static IP addresses is to set the workstations and printers to DHCP and create reservations for them on the DHCP server.
 

mr_zen256

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Not to belabor the point, but still being able to access the Internet and ping devices on the network is really a key piece of information. It means that your "network" connection isn't down, and that everyone here has been trying to help you solve the wrong issue.

So, to clarify the issue... The problem is that you're losing access to SMB mapped network shares? What's hosting the share? WIndows Server 2003/2008/2012 or Linux? What happens when you try to access the share on the affected client through Windows Explorer by name (instead of using the mapped drive). Use the syntax \\servername\sharename in the Explorer address bar, or through Start > Run

Are there any errors in the Windows client's event logs?

Thanks guys, my apologies if I haven't been entirely clear on the issue up to this point.

The share that is being lost, whether it be a mapped network drive, or a network share belongs to our file server which is a QNAP nas device (Samba). It doesn't matter if the server has been shared by name or IP address, the share will still intermittently drop out.

Again, when the drop out occurs, all other devices on the network disappear from the network explorer aside from one other windows machine (still able to ping devices however).

Will attempt to connect to the share via explorer address bar today.

We are using a Cisco 887VA-W for DHCP server.
 

memphis_1220

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I encountered a problem a couple of years ago on one of our remote sites (no IT person onsite). We had reports of network connectivity issues with Windows 7 computers onsite. All non Windows 7 computers (XP, Vista, etc) were connected to the same LAN, same switch, with no problems. We noticed the Windows 7 computers kept losing network access for a few seconds and then came back up on its own. We updated drivers, changed cables, the usual. We then discovered ARP leaks between the LAN and public networks. A few days prior, someone had noticed a cable unplugged in the comms cabinet and decided to plug it back in somewhere. They ended up bridging the LAN and WAN side of the firewall with a network cable. As soon as we unplugged this cable, the problem went away.
 

mr_zen256

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Dropping in to update anyone that has been following this issue.

The workstation has not dropped the network fileserver share since disabling MSE and disabling TCP autotuning as suggested by systemx and d2thez respectively. So, the workstation has effectively had 3 solid work days without the share being lost.

I'm hoping the most recent changes stick but I'll give it a week and avoid any false sense of security :)

Thanks to everyone that contributed to help solve this problem. I really appreciate it!
 
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