Question PC suddenly doesn't recognize Ethernet connection / cable ?

Apr 11, 2022
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A few days ago I reinstalled win10 freshly onto my desktop PC as I had some issues going on. Since then (and I think shortly before that as well, while trying to avoid reinstalling win10) my ethernet connection stopped working. I tried it all - different cable, reboot (a million times), deinstall drivers etc. - I even got myself an USB to ethernet adapter and installed those drivers but still no luck whatsoever. My ethernet does work fine on my laptop. I am lost at this point and don't know what's going on with my PC, please help if you can.
 

Darkbreeze

Retired Mod
So, after installing Windows, did you go to the motherboard's product page on the manufacturer's website, download ALL of the most recent drivers available there for chipset (.inf), network adapters, audio chipset, etc. and install them, or are you riding on the Microsoft supplied Windows drivers for all of the motherboard's onboard hardware?
 
Apr 11, 2022
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So, after installing Windows, did you go to the motherboard's product page on the manufacturer's website, download ALL of the most recent drivers available there for chipset (.inf), network adapters, audio chipset, etc. and install them, or are you riding on the Microsoft supplied Windows drivers for all of the motherboard's onboard hardware?
Already did that, no luck sadly
 

Ralston18

Titan
Moderator
Clarify: "My ethernet does work fine on my laptop" - using the same wall jack as the PC - correct?

If possible try connecting the PC to the network using another wall jack or directly to the modem, modem/router or router. Determine if connectivity returns.

The problem may be a loose or disconnected wire in the wall jack or perhaps on the other end - likely a patch panel.

The next consideration would be the network adapter's configuration. If you did not intentionally go into the network adapter's configuration settings and reset them to match the required network configuration then there will be no connectivity.

Make and model information for modem, router, or modem/router if combined.

Run "ipconfig /all" (without quotes) via the Command Prompt.

Post the results.
 
Apr 11, 2022
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Clarify: "My ethernet does work fine on my laptop" - using the same wall jack as the PC - correct?
yes same wall jack

Make and model information for modem, router, or modem/router if combined.
How exactly do I do this when using a shared internet connection? I'm living in a student apartment / building and the landlord provides everyone with internet through the same connection - i don't have a router myself.
 

Ralston18

Titan
Moderator
The landlord has a router somewhere that serves everyone in the apartment / building with internet.

Probably something similar to the following line diagram.

ISP ---> Building router --- Ethernet cables ---> Patch panel ---- Ethernet cable ---> to individual room Ethernet wall jacks.

Landlord/Manager having the necessary Router admin rights to configure the router and control access.

= = = =

If the wall jack is working with the laptop then it is likely that the Windows 10 reinstall changed the PC's network configurations to some default values.

When you moved in, did you receive any instructions that explained how to connect to the apartment's network?

Use those instructions and reconfigure the PC accordingly.

Or use the laptop's network configuration settings as a guide.

The necessary information is shown in the laptop's "ipconfig /all".

Otherwise, you will need the landlord's assistance to restore the PC's network connectivity.
 
Reactions: ethernetissue

dwd999

Honorable
A few days ago I reinstalled win10 freshly onto my desktop PC as I had some issues going on. Since then (and I think shortly before that as well, while trying to avoid reinstalling win10) my ethernet connection stopped working. I tried it all - different cable, reboot (a million times), deinstall drivers etc. - I even got myself an USB to ethernet adapter and installed those drivers but still no luck whatsoever. My ethernet does work fine on my laptop. I am lost at this point and don't know what's going on with my PC, please help if you can.
It helps to figure out if its a hardware problem or software problem. You could try this: download a linux live distro and boot from a usb containing that. If you get a connection its definitely a windows problem; if not your computer's lan chip or motherboard may be failing since you say this happened before your windows reinstall. (Do you happen to recall if during the windows reinstall the installer detected the lan connection; if not it would be another indicator that its hardware). (Also do your laptop and desktop have the same make and model lan chip). Possible worse case scenario is you could get a lan card for your desktop; might work better than usb to lan adapter.
 

Darkbreeze

Retired Mod
Man, if you have a rental agreement that includes internet, and you're not able to get that, seems to me like in every state that I know of, landlord needs to handle making sure every tenant is able to utilize that service or else pay to make sure it happens. Within reason of course. Have you even asked or elevated it like that?
 
Apr 11, 2022
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Run "ipconfig /all" (without quotes) via the Command Prompt.

Post the results.
Here you go

Interestingly enough, after manually changing the IPV4 settings my PC said it recognized the Ethernet cable and seemed to have a connection for about 5 seconds.

View: https://imgur.com/a/vQjrK0f


It's in German so I hope it doesn't confuse you too much

I tried changing it from the manual input back to automatic and it again showed it "connecting" (i tried getting to google.com but no luck)


Another thing that might help, i just tried to run the windows help tool and it told me to reset my settings etc and i did a restart. Now the ipconfig /all looks different but I'm a newbie to this so idk what is better so here's another picture.

View: https://imgur.com/a/4fEMswk


Before it told me something else when I ran the diagnostics tool (i sadly don't remember it anymore) but now it just tells me to reset my settings and that the program cannot determine the cause for the error

I did all this without my USB adapter btw
 
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Ralston18

Titan
Moderator
Not sure about that Killer Ethernet adapter - I believe that there have been problems with them. For the moment, let's set that aside for now.

The first and second "ipconfig /all" results indicate that Windows was not receiving an IP address from the network router. Note the 169.254.191.91 IP address that Windows is assigning to itself when an IP address is not received.

The third "ipconfig /all" image shows that your PC is being assigned an IPv4 address of 192.168.18.100 from a router ( gateway) using IP address 192.168.18.1 - subnet mask being 255.255.255.0 That is much more what would be expected.

[The lease time is only four hours, functional but problematic. Lease time is also controlled by the landlord's router.]

What to do:


Ensure that only one wired network adapter is enabled on your computer. Disable any other wired or wireless network adapters.

Disable IPv6.

Ensure that the network's card's speed and duplex settings are at "Auto".

Confirm, via the landlord or other tenants on the provided network that the host router's IP is indeed 192.168.18.1

However, once connectivity is established and nothing else gets changes any further losses of network/internet connectivity are likely a loose connection somewhere. Or perhaps a failing network adapter.

Try the USB adapter (USB < -- > Ethernet) again. Be sure to disable the Killer network adapter.

If the connectivity is restored and stable then the problem is likely that Killer network adapter.

Otherwise the problem is somewhere between the landlord's router and the wall jack.
 

Darkbreeze

Retired Mod
I had problems with the Killer adapter on my Z170 boards. Fortunately those boards also had Intel LAN on them as well and was able to use them because I continuously had one problem or another if I tried to use the Killer ethernet adapter.
 
Apr 11, 2022
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Not sure about that Killer Ethernet adapter - I believe that there have been problems with them. For the moment, let's set that aside for now.

The first and second "ipconfig /all" results indicate that Windows was not receiving an IP address from the network router. Note the 169.254.191.91 IP address that Windows is assigning to itself when an IP address is not received.

The third "ipconfig /all" image shows that your PC is being assigned an IPv4 address of 192.168.18.100 from a router ( gateway) using IP address 192.168.18.1 - subnet mask being 255.255.255.0 That is much more what would be expected.

[The lease time is only four hours, functional but problematic. Lease time is also controlled by the landlord's router.]

What to do:

Ensure that only one wired network adapter is enabled on your computer. Disable any other wired or wireless network adapters.

Disable IPv6.

Ensure that the network's card's speed and duplex settings are at "Auto".

Confirm, via the landlord or other tenants on the provided network that the host router's IP is indeed 192.168.18.1

However, once connectivity is established and nothing else gets changes any further losses of network/internet connectivity are likely a loose connection somewhere. Or perhaps a failing network adapter.

Try the USB adapter (USB < -- > Ethernet) again. Be sure to disable the Killer network adapter.

If the connectivity is restored and stable then the problem is likely that Killer network adapter.

Otherwise the problem is somewhere between the landlord's router and the wall jack.
Just to make sure, i proceed with all the info from my laptop (IPV4) put in - not selecting manually - correct?
 
Apr 11, 2022
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I had problems with the Killer adapter on my Z170 boards. Fortunately those boards also had Intel LAN on them as well and was able to use them because I continuously had one problem or another if I tried to use the Killer ethernet adapter.
Yeah I've read about the issues as well, I'm just so confused because it happened so suddenly. Worst case - I'll get a new Mainboard that does the trick. Still annoying though ngl
 

Ralston18

Titan
Moderator
Hold on getting a new Mainboard (aka Motherboard).

Reply to:

"Just to make sure, i proceed with all the info from my laptop (IPV4) put in - not selecting manually - correct?

No - you do not want to use or configure a manual (static) IP address. Your desktop PC desshould be requesting and receiving an dynamic (DHCP) IP address from the router.

Configure the desktop PC's wired network adapter to match the laptop's configuration. All should be the same.

The desktop will request a DHCP IP address from the router and be assigned an unused DHCP IP address within the DHCP IP address range allowed to the router.

Bear in mind that you are may need assistance from the landlord - Why?

The router may be configured to provide X number of DHCP IP addresses. Could be that the number of network devices at any given time may exceed X.

And the landlord may be monitoring and blocking devices that are not recognized as tenant devices.
 
Apr 11, 2022
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Hold on getting a new Mainboard (aka Motherboard).

Reply to:

"Just to make sure, i proceed with all the info from my laptop (IPV4) put in - not selecting manually - correct?

No - you do not want to use or configure a manual (static) IP address. Your desktop PC desshould be requesting and receiving an dynamic (DHCP) IP address from the router.

Configure the desktop PC's wired network adapter to match the laptop's configuration. All should be the same.

The desktop will request a DHCP IP address from the router and be assigned an unused DHCP IP address within the DHCP IP address range allowed to the router.

Bear in mind that you are may need assistance from the landlord - Why?

The router may be configured to provide X number of DHCP IP addresses. Could be that the number of network devices at any given time may exceed X.

And the landlord may be monitoring and blocking devices that are not recognized as tenant devices.
Thank you for the info but the landlord doesn't do anything about wifi - they just provide connection and about the rest they don't care as they got no knowledge for that.
I have a few devices I've connected to the port since and it all worked so at this point I'm pretty sure the motherboard is the issue, the PC has had some issues before already as i stated way back in the first post.

Tried it all yesterday and nothing worked, not with the Ethernet cable nor with the adapter. I ordered a new Mainboard now which i can return should it really be due to the connection itself - thank you all for your help and I hope i don't have to post in this thread again next week because it still doesn't work 😅
 
Apr 14, 2022
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I remember a thing like that for old mobos with onboard Atheros controllers. If your OS didn't recognize the LAN connection - you can active the "LAN option ROM" or similar option in the BIOS and set it as a boot option right before the Windows boot loader. It will perform a low level initialization and connection and Windows should recognize the connection properly.
 

Darkbreeze

Retired Mod
These days that's called "Network stack" and it absolutely should not need to be enabled in order for Windows to see and use any onboard or add in card network adapter. It's only generally necessary to get the network adapter to function in pre-Windows environments, or pre-OS environments to be more accurate.

Otherwise it's generally listed on modern hardware simply as enable or disable onboard LAN. You would generally only want it disabled if you were using an expansion network adapter card or some other form of adapter like wireless.
 
Apr 11, 2022
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These days that's called "Network stack" and it absolutely should not need to be enabled in order for Windows to see and use any onboard or add in card network adapter. It's only generally necessary to get the network adapter to function in pre-Windows environments, or pre-OS environments to be more accurate.

Otherwise it's generally listed on modern hardware simply as enable or disable onboard LAN. You would generally only want it disabled if you were using an expansion network adapter card or some other form of adapter like wireless.
Is there any downside to activating it then? I mean it wouldn't hurt to try it but ofc if it has security risks or smth I'd rather avoid that
 
Apr 11, 2022
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So I got an update: i just started my PC figuring I'd just try the bios network enabled tip because why not but figured I'd try to see whether it works one. Last. Time.
Well guess what? I had the cable network disabled because last I'd tried the adapter. So I activated it, waiting for the typical failure and... It works?! I literally changed NOTHING. I do not understand it at all. Do I cancel my order for the motherboard? Because what if it's just a temporary thing? I'm so confused.

Edit: so I've got a theory. I've gut a Phillips hue bridge and the third light had been blinking for a couple days despite everything working fine - didn't think anything about it. When I came home today it didn't, all three lights were on, no blinking.
Same day first time i turn on the PC again connection to the internet works.
I sadly don't have enough knowledge on this topic but could this have been connected (as in the provider / router had an issue for a few days all along) or is that not logical? (Ethernet worked fine on my laptop all the time btw)
And if it is i'd love if someone could explain to me what exactly because maybe next time this happens (if it does) i can use that info to fix the connection right away.
 
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Darkbreeze

Retired Mod
I did nothing, and it WORKED.

It's not the first time we've seen that and usually it's because Windows updated a driver in the background that you didn't even know you NEEDED to update, but did. And then, poof, the magic dragon. Ok, not poof, but you get the idea. (It's puff the magic dragon, for the uninitiated)
 
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