PC Ethernet, no Internet

[metrologist]

It's been happening sporadically, when I boot my PC, there is no network/Internet. I have a yellow triangle on the network icon in the system tray. Always when I reboot, it comes up fine.

Any ideas how to investigate/resolve this issue?

[TomS_]

What particular problem is it reporting, or is it a generic message suggesting you have no connectivity?

Basic tests:

Check the status of the NIC and see if it has received a DHCP lease from your router. If not, you might also try rebooting the router and "repair" or diagnose the connection on the PC. What about repairing it while it has the little triangle without rebooting, does that help?

Open up the command prompt and ping by IP address and by hostname, e.g. 8.8.8.8 and google.com. If you can ping by IP but not by hostname, then there is a DNS related issue. The "you have no internet" message might be due to a small service that runs on the PC not being able to contact a server out on the Internet to test its connectivity, so it assumes there is a problem.

Perhaps try using different DNS servers, like 8.8.8.8 and 8.8.4.4. Ive never really trusted the built in DNS server that comes with most routers, and always specify my own DNS servers (probably mistrust caused by early routers that had issues) or these days run my own on a Raspberry Pi.

Try using wired instead of wireless and see if that makes any difference.

Try a different router to see if that helps in any way.

Just a few things off the top of my head.

[metrologist]

I believe there is no connection to the router, so I cannot access the gateway, like the cable is unplugged. It kinda comes in spurts, so it may be a month or two, and then a few times in a week.

What happened the other day was different, I believe there was a red exclamation mark in the tray over the network icon. Rebooting did not help and I verified with another device that there was no connection to the internet.

The NIC is on the MB, so I hope there is not something going there.

[wraper]

You did not mention hardware used. What Ethernet chip is on motherbuard? For example, Intel 82579V had a silicon bug which may cause this on some motherboards.

[metrologist]

82579V 

There has to be a way to blame MS for it...

https://steamcommunity.com/discussions/forum/11/1319962683445121114/

Isn't MS supposed to update my stuff for me? I mean, they helped FTDI brick my arduino clones, but they won't patch my NIC?

[metrologist]

I just hate the way things are. The upgrade won't install without uninstalling first. Silly.


Now Win10 has everything I ever remembered about computers upside down. What am I supposed to uninstall? Do I just go to device manager and uninstall the network adapter? Or do I go to the "gear" and look in System? Is it in the Network settings? Certainly, it's not an App!!! But of course, there is Intel Network Connections listed in there. i would not be surprised if that wasn't it, and uninstalling it just borks me good! I don't even remember where that came from, not 90% of the rest of what's listed in Apps...

[wraper]

82579V 

Then try this:
https://downloadcenter.intel.com/download/22026/NVM-Update-Utility-for-Intel-82579V-Gigabit-Ethernet-PHY-Network-Connection
If firmware update does not help (it did not in my case), you have such options:
1. replace IC (which I've done), best would be with 2013+ date code. Although even with affected ICs it's a lucky combination of particular IC specimen and motherboard.
2. disable / re enable ethernet device on startup, it can be automated and AFAIK some people have done this.

here has to be a way to blame MS for it...

Intel said it depends on used OS as well. But it's Intel to blame for the bug in the chip.
EDIT: you could also try updating motherboard bios as newer version may have some measures implemented to mitigate the issue.

[Buriedcode]

There could be any number of things wrong. A yellow triangle with an exclamation mark indicates no network access, not a cable unplugged.  That would be a red circle with a white x in it for windows 10.
Generally this isn't "Hardware" problem, its a DHCP/network problem. Updating drivers probably won't hurt but I don't see why that would help unless they had become corrupt (in which case I'd worry more about your failing HD).

Have you tried a different router? or if you're convinced its hardware related, tried a different port on that router?

I'm not sure how you've debugged network settings on windows before but it hasn't changed in windows 10, except perhaps the control panel has become a bit 'basic' (as in its designed for people who don't really know about computers, which is probably the majority of users, so it has hidden control panel features).

Before you mess with drivers, just hit thh windows key and type 'network' then enter, and it'll bring up  "Network and Sharing center" from there you can click 'local area connection' and then "details" at the bottom left.  That will tell you your current IP (either what you've assigned in static, or what has been assigned by your router via DHCP), default gateway (your routers IP).  Hopefully it'll be something like 192.168.0.x

If not, then it is possible that you haven't been assigned an IP and therefore cannot connect to the network, but there really are many things that could prevent it, with 'bloody windows 10' being just one of them.  Occasionally I've had situations where an IP just wouldn't be assigned, and in that case I added a static IP, manually entering everything. That isn't advised and shouldn't be needed, but it you've tried everything else..

[paulca]

Generally this isn't "Hardware" problem, its a DHCP/network problem. Updating drivers probably won't hurt but I don't see why that would help unless they had become corrupt (in which case I'd worry more about your failing HD).

I'd go with this first.  Router is not assigning the PC it's network address details, most likely.

Reboot until it does work, then follow Buriedcode's directions into the network connection details.  Write down the IP address, Gateway address and DNS server addresses.  Then switch from Automatic to manual and type those details back in.

Does that fix the issue?

Do you have any other devices in the house that use internet?  How are they coping?

[wraper]

Generally this isn't "Hardware" problem, its a DHCP/network problem. Updating drivers probably won't hurt but I don't see why that would help unless they had become corrupt (in which case I'd worry more about your failing HD).

I'd go with this first.  Router is not assigning the PC it's network address details, most likely.

No, most likely, it's a known issue with intel 82579V ethernet chip. It can be checked by opening device manager and looking for network adapter when it failed to work normally. It should be with exclamation mark and will show error code 10 in device status.

[metrologist]

Everything else works fine. I will wait for the problem again and do a little more digging. Thanks.

[GreggD]

If the motherboard is old it could be bad electrolytic caps. Look for bulged tops.
I replaces a few of mine and got Ethernet back.

[Jwillis]

Had this happen before.Turned out to be corrupted drivers for the Ethernet. Try uninstalling and a clean reinstall of the drivers.   

[paulca]

The main issue here is lack of diagnostics.  I'm not a windows user, so my windows diagnostic skills are weak. 

When I am resolving network issues I follow up the stack (well, maybe back down it, if http://www.google.co.uk/ works there is not point going lower.

Physical
Connectivity - it's physically connected (wired only obviously) and you have a "LINK" light both ends of the cable?  Does wiggling the connectors cause link light instability? 
You can exclude the OS completely by checking the Ethernet LINK light status when at the BIOS post screen.

OS Hardware layer - Does the OS see the the device?  In Linux the first place to look would be "dmesg" or "lspci" for the hardware ident and driver selection.  In windows  I would assume Device Manager or maybe a payware hardware diagnostics/monitoring tool like Everest?  If the device is missing here, use another network connection (your phone?) to google the motherboard, network adapter name and "Problem".

Link layer - Does the Ethernet device appear to be function?  In Linux "ifconfig" will show Ethernet devices whether connected or not and show most of their internal state.  You 'might' be able to get some of this in the network connection properties or details dialog in Windblows.  You should see stuff about "Link state" and a hardware address like "fc:aa:14:26:64:1b".  You might also get useful things like Tx/Rx packets/frames and importantly Tx/Rx errors.  Anything wrong here could be hardware, cables, firmware or driver related.  As the first is not going to easy, save buying a new card, you swap cables/switches, update the OS drivers or search for known issues such as mentioned in this thread.

Network Layer -
Assuming "IPv4" does the device have an IP address?  In windows you can get this with "ipconfig" at the CMD prompt.  In linux "ifconfig" again.  Does the address look familiar or "normal", eg:  192.168.x.x,  10.x.x.x,  or 172.16-32.x.x,  if it's  a 169.x.x.x address it's likely a dummy and you have a problem.  If it's 0.0.0.0 or blank then you have no network layer setup. 

If you don't, you can assign one, but you will need to know the address and mask of the router.  However this should be auto assigned. WARNING!*

Do you have a default gateway?  This is your router IP for 99% of Domestic/SOHO set ups.  It should be assigned automatically, see the warning.

Can you ping your own IP, can you ping the router IP?  If yes, you don't have a problem with the IP layer.
Can you ping 8.8.8.8?  If yes, you have internet too.
Can you ping google.co.uk?  If yes, the internet is fully working, you have an application or firewalling issue.

Transport Layer - TCP/UDP connections.  Unlikely to go wrong on it's own in domestic / SOHO setups but could be firewall issues.

Application layer - DNS is the lowest level service without which the internet doesn't work very well.  It also should be auto assigned.

If you can ping 8.8.8.8 but not google.co.uk you probably have a DNS issue.

*WARNING:  DHCP is the thing that gives devices network settings automatically.  Routers typically tell new devices to use it's network, assign it an IP address, tell it the default gateway and the DNS servers.  It is also finickity and can ruin your day when it goes wrong.  Here's why:

Do you have more than one router in your network?  More accurately do  you have more than one device which runs a DHCP service?  These would include routers, cable modems, Wifi Access Points and a number of others.

If you have more than one DHCP server, unless they are configured properly, it will be pot luck as to which one answers the new device.  If the wrong one answers, chances are it will issue poor or unusable settings, such as "default gateway" and DNS servers.

I have a separate ADSL model and Wifi access point.  For the first few months everything worked great, then randomly I stopped getting the correct IP address or default gateway and had to restart the network interface (or reboot).  Knowing what I'm doing it didn't take me long to narrow it down to the WiFi access point having a DHCP server. 

So how do you fix it?  I configured the Wifi access point to forward DHCP requests to the router.  The alternative is to turn the DHCP service off, if you can, configure it's server IP address range, gateways and DNS manually or... just assign your own IP addresses on the OS manually.  The later removes DHCP completely from being an issue ever again, but is less and less practical with more and more IP devices showing up in your home, Sky boxes, TVs, mobile phones, IoT devices etc. etc.