[SOLVED] Random internet drops on wired connection - WiFi unnafected

marmalade24

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Dec 23, 2020
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Hello,

I kinda need a hand with this. This issue has been present since at least early 2021, but it's escalated to the point where it happens pretty much everyday. It's also survived across three Windows clean installs, and as stated in title WiFi connection is unaffected (I'm wired on my Desktop PC).

Internet just drops for a few seconds, randomly - it can be stable for a few hours and then all of a sudden drop several times in a matter of few hours.

This is what I tried so far with no success:

  • Running sfc /scannow.
  • Checking router signal levels (all OK).
  • Checking router event logs (nothing relevant).
  • Swapping ethernet cable between different LAN ports.
  • Replacing the ethernet cable.
  • Disabling proxy.
  • Disabling network discovery.
  • Disabling smart multi-homed name resolution via GPO.
  • Disabling IPv6.
  • Preventing Windows from turning off the adapter to save power.
  • Running ipconfig with /flushdns /release /renew arguments.
  • Resetting winsock.
  • Reinstalling the network adapter.
  • Updating the network adapter driver.
  • Changing DNS to Google's.
  • Changing DNS to Cloudflare's.
  • Checking connections and physical damage in the motherboard (except CPU socket itself)
I probably forgot something but it's all I can remember for now. Thought replacing the cable would make the trick but clearly it didn't, and I don't think it's a faulty network adapter since it responds to pinging all the time. As router signal levels are within normal values I also believe it's unlikely ISP is the culprit here. What I also noticed is the network adapter at times would negotiate only 100 Mbps even though is Gigabit. I'm not sure if this is normal behavior.

I'm pretty much clueless at this point. Any help? If you need any logs let me know.

Thanks in advance

=== Specs and additional info ===

MOBO: GA-H81M-H (rev 1.1)
CPU (iGPU): Intel Core i5-4430 @ 3.0 GHz (HD Graphics 4600)
dGPU: XFX AMD Radeon HD 6570
PSU: Generic 500W (included w/case)
OS: Windows 10 21H2 (19044.1526)
Network adapter in use: Realtek PCIe GBE Family Controller (on-board)
Driver version: 10.1.505.2015

=== Router info ===
Model: Sagemcom F@st 3890 v3 (all-in-one) (# of LAN ports: 4)
Number of connected devices: 7 at max including one Laptop, one Desktop, Chromecast and four mobile phones (not sure it's the problem since it's been this way for years and never had this issue before)
NAS and/or server connected: No

=== Errors ===
I observed two possibly related events recorded in Event Viewer:

Warning, DNS Client Events, ID 1014, Name resolution for the name <URL> timed out after none of the configured DNS servers responded (it can be any URL but most of the time it's just 'wpad').
Error, DHCPv6-Client, ID 1000, Your computer has lost the lease to its IP address <network_card_ipv6_Adress> on the Network Card with network address <network_card_Address>.
 

IanG367

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Nov 18, 2013
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Might be worth checking the documentation for your router and for your LAN card to ensure that you do not have an Ethernet Duplex mismatch.

Results can be crazy if one end half duplex and the other end is full duplex.
The auto feature is akin to plug & pray. If you SET IT on both ends, you know what it is supposed to be.
 

dwd999

Honorable
I didn't see you mention this: Did you go through the Control Panel Power Options and set everything to Maximum always on? Did you go through the Device Manager for all devices related to internet and make sure the Power Management box was Unchecked so that the windows wouldn't shut it off?
 

IanG367

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Nov 18, 2013
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Might be worth checking the documentation for your router and for your LAN card to ensure that you do not have an Ethernet Duplex mismatch.

Results can be crazy if one end half duplex and the other end is full duplex.
The auto feature is akin to plug & pray. If you SET IT on both ends, you know what it is supposed to be.
 

marmalade24

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Dec 23, 2020
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I didn't see you mention this: Did you go through the Control Panel Power Options and set everything to Maximum always on? Did you go through the Device Manager for all devices related to internet and make sure the Power Management box was Unchecked so that the windows wouldn't shut it off?
Yes, I checked both.

Might be worth checking the documentation for your router and for your LAN card to ensure that you do not have an Ethernet Duplex mismatch.
I can't find much info anywhere. Is there other way to check this?
 

marmalade24

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Dec 23, 2020
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Ok, I think I figured it out.

For some reason the adapter is flip-flopping between 100 and 1000 Mbps, and it appears it's the root cause of the drops. I just went to Device Manager, selected the Network Adapter, went to Properties and then the Advanced tab. From there I selected Speed & Duplex and changed the value from Auto Negotiation to 1.0 Gbps Full Duplex.

I'm going to wait a few days and let you guys know if that works.
 

IanG367

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Nov 18, 2013
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Yes, I checked both.



I can't find much info anywhere. Is there other way to check this?
Some years ago I came across this issue while working on a major windows network that had gone from TRII to Ethernet.

It took us ages to figure out what was going on but IIRC the actual RFC for auto negotiation has this as a known fault. You see huge degradation of the stream of data from a half duplex to a full duplex port. At certain points the degradation of the connection will start causing timeouts on TCP and IP functions because of the low through-put.

I recall it being really hard to get a handle on what was going wrong as most non proficient users might expect Auto to be capable of sorting this out. As I understood it the problem existed with all switches from a 4 node cheap home setup to the top of the range Cisco machines.

As it is a long time ago I do not remember chapter and verse on it but I expect that you will find most documentation explicitly tells you to set both adapters to the same setting. Auto/Auto Full/Full Half/Half

I only mentioned it as a bell went off in the back of my head about how frustrated I was when I came across it.
 

marmalade24

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Dec 23, 2020
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Well setting it to 1Gbps Full Duplex didn't work. Trying 100 Mbps Full Duplex now.

At this point I'm thinking in a bad router or the adapter going under. I will keep you posted.

Thank you for all the help so far!
 
It is actually very rare for port in a router or pc to be bad. Most times they just do not work at all but they do get strange failures it is just very uncommon.

You need to always leave the settings on auto. Since you can generally not set this to anything else on home router when you set the pc to something other than auto the router port can get confused. You would need to manually set both ends the same to use the other options.

This is almost always a bad ethernet cable. The speed stuff is done at a very low hardware level based on voltages and such and is not really a software function. The problem is a bad ethernet cable can work on some machines and not others and they can work correctly for a while and then not.

It is almost always related to poor contact internal to the RJ45 plugs and not the wires themselves. BUT there is also massive amounts of fake ethernet cable on the market. The most common is that flat cable. That has wires that are too thin to meet the standards for ethernet cables.

Then again even the best cable can somehow get damaged. I would try a new cat5e or cat6 if it cheaper. The key thing is to buy pure copper cables (no CCA) and make sure the wire size is 22-24 awg. If the seller does not specify this information look for other cables.
 

marmalade24

Prominent
Dec 23, 2020
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I ditched my old Cat 5 cable and replaced with a Cat 6 and the issue still persists so I don't think the problem's there. Unless I'm extremely unlucky and purchased a defective cable.

Anyway, capping the adapter to 100 Mbps seems to work. I had no drops in the last 24 hours which is a lot compared to before. No issue for me since my ISP provides a 50 Mbps connection so I guess it's a fair workaround.

For a proper solution I should actually contact my ISP to ask for a router replacement or buy a PCIe card but honestly I had enough troubleshooting for this week (and month).

Marking IanG367's answer as the best since his guidance helped me a lot.

Thank you guys for the assistance!
 
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