Question Can't connect to some services after power outage ?

[rflection]

This is a contender for the weirdest thing that ever happened to one of my computers.

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Summary: Power went out for a bit, then I couldn't access some websites and services on both my OSes (everything works fine on other devices in the same network), tried resetting DNS, rebooting PC and Modem multiple times but nothing works.

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I was using my computer normally (playing a game on Steam while on Discord with some friends), when my whole block got a blackout. It was really quick, after a couple seconds had passed the power went back on, but when I restarted my PC the first sign of doom happened: Windows detected a new network for my cabled connection. After that I couldn't connect to Discord or Steam (they start automatically), then I tried my browser and I could use Google, YouTube and Wikipedia, but many other sites like Reddit or Tom's Hardware didn't load.

Then I tried changing DNS (tried Google's, OpenDNS' and Quad9's), clearing DNS cache, rebooting the computer and the modem multiple times in different orders, and changing the modem's port, but Windows still accused a problem with the DNS. Meanwhile, my wife's computer (also cabled) and my phone (wifi) worked just fine. Then I tried rebooting and changing to my Ubuntu installation and the same problem happened, tried the same fixes and still nothing works.

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So, could it be possible that the sudden power outage damaged my Network Interface Controller? If yes, can I fix it or should I replace my motherboard? if no, what could it be and what can I do? Thanks in advance!

 

[bill001g]

The network interface is pretty simplistic it does not really understand the concept of web sites. In fact it is so simple it does not even know what a IP address is, it function purely on mac addresses and software function in the OS does everything else.
Problems with a ethernet port tend to be packet loss which causes poor performance on all sites.

It is strange it affects multiple OS like Ubuntu. Windows can be very stupid sometime and decide you are now running on a public network and set the firewall rules higher so some stuff no longer works.

The other common thing that causes this is IPv6. Not sure why it would all the sudden start to happen but I would try to disable IPv6 in the network settings and see if it fixes it.

 

[rflection]

I know that NICs only work with packets and at most understand addresses and protocols, but since other devices have no problems (so shouldn't be a ISP or modem problem) but both of my OSes have, together with the fact that Windows recognized a new network made me suspicious of it.

On the troubleshooting: IPv6 was already disabled, I enabled and re-disabled, problem still happens. Also disabled the firewalls entirely to no avail. Rebooted with these settings, they persisted but so did the problem. Did the same thing on Ubuntu, also no improvements.

What caught my attention is that while Steam, Discord and many websites don't work on both OSes, the Telegram app works on Ubuntu but not on Windows.

 

[bill001g]

Not sure the main difference between something steam or discord is they do not use the same ports as html/htmls. That doesn't explain why some web sites might not work.

Do they consistently stay broken or are they random.

You should be able to manually check some of this with the NSLOOKUP and ping commands.

I would try the nslookup both using the default dns and then force it to use 1.1.1.1 or 8.8.8.8. Maybe the IP addresses it resolves to is different. You can also try to ping the various IP. It would be very strange if you can look up a IP with nslookup and then ping it but browser would fail.

 

[rflection]

The sites and services that are broken are consistent, can't access them in any way, but Windows sometimes doesn't detect that it's connected. I also can't access my modem's interface page from my computer.

So, I did a bit more of testing, tried using my wife's computer's cable and it still didn't work, so I dug up an old USB WiFi adapter I have, tested it and everything worked. This reinforces my suspicion that the problem is in my NIC (or something related to it), but it seems extremely weird to me that I can access some sites but I can't even access my modem's page when cabled.

 

[bill001g]

Did you use the IP address or some name to access the router.

You would think DNS issues would affect both ethernet and wifi. Ethernet issues should cause messages in the event viewer. If you have a empty slot in the machine a pcie ethernet card is fairly inexpensive but I can't see how a hardware failure would only break some sites and not others.

 

[rflection]

I used the internal IP address, 192.168.0.1.

I've checked the Event Viewer, there was an error from "DHCPv6-Client" about losing lease to the IP address, and another from "NetBT" saying "initialization failed because the driver device could not be created", but both of those also happened before the power outage and I had no connection problems. Then I looked into other related logs and found a lot of warnings from "DNS Client Service" saying that name resolution timed out for multiple addresses (firebase, steam, microsoft sites, dns.google and a couple more), so to Windows it is indeed a DNS problem. And then I also found many errors from "Dhcp-Client" saying that "Nack is received on the interface 4", which I couldn't find any from before the power outage problem, and they started right a couple minutes after the kernel log saying that the last shutdown was unexpected.

Unfortunately my MotherBoard is a Mini-ITX, so there aren't any vacant PCIe slots. If the problem really is my NIC I'll have to settle on using a USB adapter until I get a new MB.

And indeed, I'm really puzzled about this whole situation, nothing makes sense and I ran out of ideas on what to test, at least I got a working solution for now, even if it's not the one that I wanted.

 

[rflection]

I researched about this Nack message a bit and found a couple of threads saying that it could cause DNS issues. Turns out it's just saying that the DHCP server (my modem, I suppose) is refusing to assign an IP address to my computer, and it is actually a NIC-modem problem, which seems consistent with my test results. Also on another thread I someone mentioned that this could be caused by a change in the MAC address, and since the MAC address can be stored in the flash memory of my NIC and the flash could be damaged by the power outage, it at least makes some sense.

This seems really promising, so I'll see if I can reset the DHCP server or make it forget my previous connection, hopefully it fixes my problem.

 

[bill001g]

Not sure why DHCP would not work correctly.

I would first try to disable IPv6 on the interface. IPv6 has lots of strange issues on its own.

The best test of DHCP issues is to set a fixed IP in IPv4 settings on the nic. You technically need to assign a IP outside the range your router dhcp gives out but say 192.168.0.250 tends to be a safer one to try. You want to avoid the router assigning the same IP to another device in your house.

In general what NACK means is the pc is trying to reuse a old IP and the router is saying no you can't have that IP. The normal function of a PC when that happens is to just release the IP and request a completely new one.