Question PC intermittently takes down entire home network ?

afurniss4

Commendable
Sep 8, 2018
5
0
1,510
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I have a very strange issue with my home network. For some reason, I intermittently get an issue where the whole network dies temporarily. The duration of the outage seems to vary but can take up to about 5 minutes to return to normality. This can happen several times a day which in this day and age - where my partner and I are working from home - can be quite disruptive. We've had several work Zoom/Teams calls cut out due to this problem which is quite frustrating.

We are based in the London and have VDSL/FTTC fibre broadband and the ISP is Uno. Usual speeds are around 45 Mbps down and 15 Mbps up.

I believe I have narrowed the culprit down to my main PC as we can spend the whole day working our work laptops with no issues but as soon as I turn my main PC on after work, the network goes down and Chrome gives me DNS_PROBE_FINISHED_NO_INTERNET. I then try running network troubleshooter which fails to fix the issue and the messages it gives me always seem to vary which is pretty unhelpful. Although it happened on the startup of my PC, it is not isolated to this event. It seems to happen sporadically when the PC is on, sometimes it seems to be triggered by myself and someone else streaming at the same time but other times it seems just happen at any random point in time.

My network setup is as follows:

  • Modem: Draytek Vigor 130
  • Router: Netgear Nighthawk R7800
  • Powerline adapter (router to wall): TP-LINK AV600
  • Powerline adapter (wall to main PC): TP-LINK AV600
  • Powerline adapter (wall to partner's laptop): TP-LINK AV600
  • Various other devices connected via wireless
My PC's specs are as follows:

  • Windows 10 Enterprise
  • Mobo: ASUS ROG STRIX B450-F Gaming (no separate network card)
  • CPU: AMD Ryzen 7 3700X
  • BIOS: AMI 2901 16/10/2019
  • RAM: Corsair Vengeance LPX 2 x 8GB
I would greatly appreciate some help with this as it's been plaguing us for over a year now and it's driving me a bit mad. I even recently spent £85 on the Draytek modem as I thought it was the crappy old Openreach modem I was using before that was the issue but that hasn't helped either.

Let me know if you need any further details from me and I will happily provide them.
 

Ralston18

Titan
Moderator
Are all the powerline adapters fully and firmly in place with respect to the host wall outlet?

Try swapping in other known working Ethernet cables between powerline adapters and connected device. Start with main PC.

Another thought - some IP address conflict.

Does your network have any devices with an assigned static IP address?

Take a close look at all network devices both wired and wireless. Use the router's admin screens to look for some listing of connected devices. There should be no duplicate IPs.

On main PC run "ipconfig /all" via the Command prompt. Post the results.

Also run "arp -a" and post the results.
 
I suspect an IP address conflict. I would try this to confirm--unplug the ethernet from the PC that is causing the issue and boot it. If everything is fine and remains fine, then it is time for test 2.

For test 2, boot a linux live cd/usb and then plug the ethernet cable back in. If everything continues to work without issue, it is an IP address conflict caused by a configuration in windows.

Remove the ethernet cable again, boot back up to windows and make sure your PC does not have any static IP address assignments and is set to dhcp only. Reboot and confirm that it is set to dhcp, and then plug in the ethernet cable and see if you have any more issues.
 

afurniss4

Commendable
Sep 8, 2018
5
0
1,510
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Thanks for the replies guys.

Are all the powerline adapters fully and firmly in place with respect to the host wall outlet?
Yes all confirmed as plugged in OK.

Here are the outputs of the requested commands:

ipconfig /all

Code:
Windows IP Configuration

   Host Name . . . . . . . . . . . . : Astronomican
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Ethernet 2:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Intel(R) I211 Gigabit Network Connection
   Physical Address. . . . . . . . . : A8-5E-45-E4-CB-D2
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::696a:3590:5264:5a9f%7(Preferred)
   IPv4 Address. . . . . . . . . . . : 192.168.1.16(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : 29 November 2020 13:06:59
   Lease Expires . . . . . . . . . . : 30 November 2020 15:51:41
   Default Gateway . . . . . . . . . : 192.168.1.1
   DHCP Server . . . . . . . . . . . : 192.168.1.1
   DHCPv6 IAID . . . . . . . . . . . : 128474693
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-25-6F-D7-97-90-2B-34-37-80-E7
   DNS Servers . . . . . . . . . . . : 192.168.1.1
   NetBIOS over Tcpip. . . . . . . . : Enabled
arp -a

Code:
Interface: 192.168.1.16 --- 0x7
  Internet Address      Physical Address      Type
  192.168.1.1           8c-3b-ad-b6-c1-ca     dynamic
  192.168.1.101         f8-0f-f9-97-4a-a9     dynamic
  192.168.1.104         6c-ad-f8-c5-47-25     dynamic
  192.168.1.255         ff-ff-ff-ff-ff-ff     static
  224.0.0.2             01-00-5e-00-00-02     static
  224.0.0.22            01-00-5e-00-00-16     static
  224.0.0.251           01-00-5e-00-00-fb     static
  224.0.0.252           01-00-5e-00-00-fc     static
  239.255.255.250       01-00-5e-7f-ff-fa     static
  255.255.255.255       ff-ff-ff-ff-ff-ff     static
I've also checked the connected devices in my router's UI. There did not appear to be any IP conflicts. I did however notice that my router is configured to use a static IP address as I received one free with my ISP deal. Could this be part of the issue? Screenshot of setting below.

 

afurniss4

Commendable
Sep 8, 2018
5
0
1,510
0
I upgraded my motherboard, CPU and RAM in March this year but I don't believe I reinstalled Windows at the time. The install date for Windows in [Settings -> System -> About] shows as 26th November 2019.
 

kanewolf

Titan
Moderator
I upgraded my motherboard, CPU and RAM in March this year but I don't believe I reinstalled Windows at the time. The install date for Windows in [Settings -> System -> About] shows as 26th November 2019.
This could be a "ghost" that is plaguing this computer because of a messed up Windows install. It could be a red herring also.
If the network outage was repeatable, then booting the computer with a Linux portable flash drive, might be a way to help identify a Windows install problem.
 

afurniss4

Commendable
Sep 8, 2018
5
0
1,510
0
After running arp -a on all other network computer's, I haven't found any references to A8-5E-45-E4-CB-D2. I've added all the outputs below.


My work laptop:
Code:
Interface: 192.168.1.15 --- 0x10
  Internet Address      Physical Address      Type
  192.168.1.1           8c-3b-ad-b6-c1-ca     dynamic
  192.168.1.101         f8-0f-f9-97-4a-a9     dynamic
  192.168.1.104         6c-ad-f8-c5-47-25     dynamic
  192.168.1.255         ff-ff-ff-ff-ff-ff     static
  224.0.0.2             01-00-5e-00-00-02     static
  224.0.0.22            01-00-5e-00-00-16     static
  224.0.0.251           01-00-5e-00-00-fb     static
  224.0.0.252           01-00-5e-00-00-fc     static
  230.230.230.230       01-00-5e-66-e6-e6     static
  239.255.255.250       01-00-5e-7f-ff-fa     static
  255.255.255.255       ff-ff-ff-ff-ff-ff     static

Interface: 172.18.17.81 --- 0x16
  Internet Address      Physical Address      Type
  172.18.17.95          ff-ff-ff-ff-ff-ff     static
  224.0.0.22            01-00-5e-00-00-16     static
  224.0.0.251           01-00-5e-00-00-fb     static
  239.255.255.250       01-00-5e-7f-ff-fa     static
  255.255.255.255       ff-ff-ff-ff-ff-ff     static

Partner's personal laptop:
Code:
Interface: 192.168.1.8 --- 0x8
  Internet Address      Physical Address      Type
  192.168.1.1           8c-3b-ad-b6-c1-ca     dynamic
  192.168.1.10          10-62-e5-7e-b7-14     dynamic
  192.168.1.15          10-65-30-9a-9a-6a     dynamic
  192.168.1.101         f8-0f-f9-97-4a-a9     dynamic
  192.168.1.104         6c-ad-f8-c5-47-25     dynamic
  192.168.1.255         ff-ff-ff-ff-ff-ff     static
  224.0.0.2             01-00-5e-00-00-02     static
  224.0.0.22            01-00-5e-00-00-16     static
  224.0.0.251           01-00-5e-00-00-fb     static
  224.0.0.252           01-00-5e-00-00-fc     static
  230.230.230.230       01-00-5e-66-e6-e6     static
  239.255.255.250       01-00-5e-7f-ff-fa     static
  255.255.255.255       ff-ff-ff-ff-ff-ff     static

Partner's work Surface Pro:
Code:
Interface: 192.168.1.13 --- 0x11
  Internet Address      Physical Address      Type
  192.168.1.1           8c-3b-ad-b6-c1-ca     dynamic
  192.168.1.104         6c-ad-f8-c5-47-25     dynamic
  224.0.0.22            01-00-5e-00-00-16     static
  224.0.0.251           01-00-5e-00-00-fb     static
  239.255.255.250       01-00-5e-7f-ff-fa     static
  255.255.255.255       ff-ff-ff-ff-ff-ff     static


My mobile phone (OnePlus 3 Android 9):
Code:
Internet: 192.168.1.103
MAC: C0:EE:FB:D9:BA:E6

Partner's mobile phone (iPhone 8)
Code:
Internet: 192.168.1.7
Phone says MAC is: D0:2B:20:80:E8:C3
Router says MAC is: 46:45:AA:85:D9:9C
I've just checked the connected devices in the router UI and A8-5E-45-E4-CB-D2 is associated with my personal PC which has IP 192.168.1.16.
 
Last edited:
Does this happen often enough you can do testing.

What you want to do is compare the results you have from your various devices when it is good to when it is broken. What would be most suspect is if the mac address for 192.168.1.1 changes. Although not very likely but if you were to see the mac address of your pc assigned to 192.168.1.1 on the other devices it can cause big issues.

If it looks ok I would see if you can ping the router IP from the various devices. This is to see if the lan is going down or if you are actually losing the internet.
 

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