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One of the Windows PCs on my home network has recently started causing network problems. I will refer to this PC as the “problem pc”.

The last thing I did to the problem pc before the issue started was a complete re-install of Windows on a freshly re-formatted drive. I have no way to ‘rollback’ the re-install to see if it fixes the problem.

When the problem PC is shut down, all devices connected via ethernet on my network lose the ability to access the internet.

Netflix, Amazon Prime Video, etc, are all unable to connect to their respective services. If you're already watching a video, it will eventually stop, presumably after its shown all the video it had buffered before the outage.

Web pages won't load at all. Chrome eventually displays a page with an error message "No Internet", a recommendation to run Windows Network Diagnostics, and "DNS_PROBE_FINISHED_NO_INTERNET". Running Windows Diagnostics tells me to "Restart your broadband modem", which does not resolve the issue.

Additionally, traffic within my home network becomes very slow. (for example, copying a file to or from my Synology Diskstation NAS)

Devices connected via Wi-Fi are not affected.

Notes:

  1. The problem occurs any time the problem PC is plugged in, but not booted up
  2. The problem will clear up if I do any of the following to the problem pc:
    a. physically remove power (unplug)
    b. press the power button to start it back up. The problem resolves almost instantly (i.e. well before the PC is fully booted up)
    c. disconnect the ethernet cable
  3. The problem PC is not
    a. sharing its internet connection
    b. running a DHCP server (or any other kind of server software)
  4. I’ve done all of the following to the problem pc:
    a. disabled “Fast Boot” in UEFI/BIOS
    b. disabled “Fast startup” in Windows “Power Options”
    c. disabled “Allow this device to wake the computer” in the NIC’s Power Management settings
    d. run

Thanks in advance for any help you can provide!

EDITS below...

Thanks to all of you who are commenting and providing direction!

@Zac67: Here is the information you advised me to get. This information was collected from my desktop PC, while the 'problem pc' was plugged in but 'shutdown', and the network outage was occurring.

"Does the problem occur if you unplug the power and replug it without turning on the PC?" : Yes

1. ping the default gateway 

C:\>ping -n 15 192.168.1.1

Pinging 192.168.1.1 with 32 bytes of data:
Reply from 192.168.1.1: bytes=32 time=295ms TTL=64
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Reply from 192.168.1.1: bytes=32 time=583ms TTL=64
Request timed out.
Reply from 192.168.1.1: bytes=32 time=308ms TTL=64
Reply from 192.168.1.1: bytes=32 time=294ms TTL=64
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 192.168.1.1:
    Packets: Sent = 15, Received = 4, Lost = 11 (73% loss),
Approximate round trip times in milli-seconds:
    Minimum = 294ms, Maximum = 583ms, Average = 370ms

C:\>

=======================

2. ping the DNS server

C:\>ping -n 15 8.8.8.8

Pinging 8.8.8.8 with 32 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Request timed out.

Ping statistics for 8.8.8.8:
    Packets: Sent = 15, Received = 0, Lost = 15 (100% loss),

C:\>

================================

3. run tracert 1.1.1.1

C:\>tracert 1.1.1.1

Tracing route to 1.1.1.1 over a maximum of 30 hops

  1   160 ms   155 ms   155 ms  192.168.1.1
  2     *        *        *     Request timed out.
  3     *        *        *     Request timed out.
  4     *        *        *     Request timed out.
  5     *        *        *     Request timed out.
  6     *        *        *     Request timed out.
  7     *        *        *     Request timed out.
  8     *        *        *     Request timed out.
  9     *        *        *     Request timed out.
 10     *        *        *     Request timed out.
 11     *        *     ScottTower2017.Home [192.168.1.112]  reports: Destination host unreachable.

Trace complete.

C:\>

Updates 7/24:

  1. I updated the driver for the NIC and the behavior has changed. Shutting down Windows no longer causes the outage. However, when I unplug the power cord, and plug it back in, the outage occurs just as it did before. As before, pressing the On button to boot the machine resolves the outage almost instantly. This behavior is still problematic... If we have a power failure, the problem will manifest when power is restored. For the time being, I'm turning off the surge protector as a preventive measure.

  2. I attached a USB ethernet adapter to the problem pc, and moved the ethernet cable from the internal NIC to the USB ethernet adapter. The problem is not reproducible. I believe that rules out any issues with the ethernet cable or downstream equipment. If all else fails, this would be a viable kludge to work around the problem.

  3. I confirmed that the "Wake On Lan" feature is already disabled in the BIOS. That appears to be the default setting. To be thorough, I enabled it, and that did not resolve the problem. I then set it back to disabled, and that did not reolve the problem

  4. I updated my BIOS firmware to the latest available, and that did not resolve the problem.

  5. In an effort to sniff the traffic coming out of the problem PC, I configured my primary desktop as a bridge between the problem PC and the rest of the network. (i.e. my desktop PC positioned as Man-in-the-middle with WireShark running) The problem is not reproducible in that configuration. I'm still trying to understand what this means for my investigation

  6. I ordered a new internal NIC to see what we can learn from that.

Updates 7/25:

  1. New NIC not here yet.
  2. Meanwhile, I decided to start from scratch: a) wiped the SSD, b) re-installed Windows 10, c) let Windows Update install a bunch of updates, and 21H1. (same as before)
    2.a) Now I'm experiencing the same symptoms while using the USB ethernet adapter. I should've tested the behavior before installing updates, especially 21H1.
    2.b) When time permits, I plan to do this process again, but not allow Windows Update to install any updates. This should help me understand if 21H1 is causing the problem.

Updates 8/1:

  1. Installed new PCI-Express NIC. Same problematic behavior.
  2. Bypassed Netgear switch. Same problematic behavior.
  3. Installed new NIC in another PC. No problem.
  4. Re-installed Windows 10, without allowing it to do any updates. The on-board ethernet adapter and new PCI-Express NIC both continue to cause the problematic behavior. The USB Ethernet adapter no longer has issues. ... Note: The USB adapter is using the same CAT 5 patch cable and Netgear switch that I was using with the other ethernet adapters. Does this imply that there is nothing wrong with those items, as well as any other 'upstream' cables & devices?

Updates 8/2:

  1. @davidgo: The router is a Calix 854G-1 provided by my ISP

At this point, I'm going to continue to turn off the power at the surge protector whenever this PC is not in use. Its a kludge, but it prevents the problem from occurring.

I won't be actively working this issue, unless someone has a suggestion.

Thanks everyone!

5
  • 1
    Try a new NIC. Ethernet NICs are rather cheap.
    – Daniel B
    Jul 22, 2021 at 19:03
  • I have to assume that PC, or its cable is introducing noise on the network, in it's low power state, which is resolved when going into high power, or when the OS takes over its management. See if you can disable Wake on Lan, and/or power management settings in the bios/uefi to power down the nic when the PC is off. The setting you already disabled is only meaningful when the system is booted and in sleep mode. and consider Daniel B's advice. replace the nic and the cable. Jul 22, 2021 at 19:35
  • Could be also something electrical like a different ground potentials which cause a current to flow which causes an involved device to behave strange.
    – Robert
    Jul 23, 2021 at 1:55
  • It would be good to get the MAC addresses associated with the network cards in the PC and router and also look at the ARP tables of the router, PC and other affected devices. I postulate some kind of weird router issue maybe? What model router do you have?
    – davidgo
    Aug 1, 2021 at 23:14
  • @Davidgo - I added the router info as an update to the question.
    – Scott N
    Aug 2, 2021 at 14:59

1 Answer 1

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First steps in connectivity troubleshooting:

  1. ping the default gateway - failure indicates a basic L1 or L2 problem (cable, switch / Wi-Fi)
  2. ping the DNS server - failure indicates a server problem (or routing for remote server)
  3. run tracert 1.1.1.1

and add the results to your question as text, using the { } function.

You find both default gateway and DNS server in the ipconfig /all output.

Your problem description does look pretty weird though. Does the problem occur if you unplug the power and replug it without turning on the PC? If not, it's possibly a bad driver (leaving the NIC in a jabbering state on shutdown) - try updating it from the vendor's support page. If it does, you might want to replace the NIC.

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