Help, Intermittent LAN

[Kith]

Hello all,

 

If I've posted this in the wrong location, sorry ahead of time.

 

I'm going to try to be as thorough as possible, but if I missed anything please free to ask.

 

 

I purchased a new PC 2~ weeks ago. It runs great, however the ethernet connection dies out randomly. It could be after 5 minutes, or 2 hours. It could work on boot, it could not work on boot.

 

I updated the BIOS, chipset, and network adapter, no difference.

 

I purchased a new ethernet cable, no difference.

 

I contacted the manufacturer, and they walked me through the same steps I had already done. At the end, they said to bring it back to Costco and just exchange it, citing a bad ethernet port on the mobo.

 

I did that, and the new computer has the same problem as the old computer.

 

When the PC stops working, I unplug the ethernet, and plug it into an old laptop. The old laptop does fine. Neither of my old pieces of gear have had this issue.

 

I also plugged in a USB-C to ethernet adapter, one which worked on my old laptop. It has the exact same issue on the new PC that the onboard has. Sometimes internet, sometimes not. Unplug/plug, sometimes fixes, sometimes not. Reboot sometimes helps, sometimes not. 

 

I'm really at a loss as to what to verify or test next. Some of the above testing makes me think it's the new computer. Some of the above testing makes me think it's something in my home network/wiring.

 

Can the community suggest anything else for me to try? I was considering installing a PCI NIC but, I don't see how that would end up being different than USB-C/Ethernet I've already done.

 

During the time it took me to write this, I connected to the internet using the onboard NIC. Part way through it died. So I moved the cable to the USB-C/Ethernet cable. After a while, that also died, and I am finishing this via wifi.

 

 

Info:

Computer

IBuyPower Element

Pro B650-VC WiFi

Realtek Gaming 2.5GbE Family Controller, Driver 10.74.1128.2024     *** In writing this I see they came out with a new driver just a couple days ago. I'm going to install that now and see if that makes a difference. Though, I don't know why this would impact say the USB-C/Ethernet trail.

 

 

Home setup:

Ethernet from the switch on the main level, routed in the walls to the port on the wall in my office downstairs. I just ordered a 100ft cable so I can try just circumventing the cables in the walls. Though, said cables in the walls serviced a different desktop, and two other laptops over the years just fine.

 

I don't know if it matters, but the WiFi has been fine.

 

[Omon_Ra]

Are your laptop/old devices you have been plugging into the same ethernet cable also 2.5GbE or just regular gigabit? Depending on the age of your router/switch, it may not like the 2.5GbE ethernet adapter. Sometimes you have to set ports to specifically gigabit (if it doesn't support 2.5GbE) and not auto-negotiate. Though I'm assuming the USB-C to ethernet is gigabit, which is definitely odd. Only other things I can think is checking if the new PC has static IP, and something else on your network will pull its statically assigned IP. Or checking your DHCP scope and making sure that's not full. Also check your wall jack, you may need to replace the keystone jack in your room. Also check the connection to your router/switch on the other end. Issues like this I always replace the physical connections in the building after replacing the ethernet cable to the wall.

[ieleja]

5 hours ago, Kith said:

I'm really at a loss as to what to verify or test next.

Event Log?

[gentlemanspot]

Can you take the computer to another network? see if it happens at someones else home

 

I want to say it's DNS!

[Kith]

Omon_Ra

The "old" laptop is a 2.5 (Killer E3100G 2.5)

The other actual old device is regular gigabit

The USB-C/Ethernet is gigabit

 

The switch gear is old, though since it worked with the other device at 2.5, and not the new one, I'm not sure. If the other troubleshooting steps done resolve it, I'll see if I can set it to gigabit and if that makes a difference.

 

It's set to DHCP, and the range isn't full, though good thoughts.

 

Checking the keystone and the cabling in the wall is on the list. Once the long ethernet cable comes in, I'll test that, circumventing the cabling/connections it's using now. Maybe this NIC is just more finicky that the others with degraded connections.

 

 

ieleja

gentlemanspot

Many warnings in the event log for DNS, though I don't know if that's causation or correlation. I need to keep better track of the timestamp of when it stops working.

Moving the PC to another network is a PITA, but another troubleshooting step I could take.

 

 

 

 

Thank you for the insight, all.

[Kith]

Thank you everyone for the help. Changing DNS specific to 8.8.8.8 and it's been working fine for over a week now. Not sure why it gets so angry with automatic, everything else works fine. Shrug.

[gentlemanspot]

On 1/2/2026 at 1:43 AM, Kith said:

Thank you everyone for the help. Changing DNS specific to 8.8.8.8 and it's been working fine for over a week now. Not sure why it gets so angry with automatic, everything else works fine. Shrug.

sounds like DNS! 

 

good chance you might have some kind of rogue DNS DHCP, you could play with wireshark. 

 

or just roll with 8.8.8.8 or 1.1.1.1 

[DraconisMaximus]

On 1/8/2026 at 12:28 AM, gentlemanspot said:

or just roll with 8.8.8.8 or 1.1.1.1 

 

If you haven't already, do this on the router / network controller as well as your individual clients.

[gentlemanspot]

fun fact!

 

In Australia, using 1.1.1.1 or 8.8.8.8 bypasses the restriction placed on the internet by the government on torrent site. 

 

.. or so the story goes