PC loses internet - help needed for troubleshooting

[Damun]

Over the last couple of weeks my PC has started losing connection to the internet/drops connection. This has happened 4-5 times now, seemingly at random.

The problem started about at the same time as i updated my router to asuswrt 386.42095 (now updated to 3.0.0.4.386.42840) but it could be unrelated.
I don't know if it's the router or my PC that's causing the problem and i hope that you guys can point me in the right direction.

My setup:

Cable Modem (Bridge mode) - Asus RT-AX86U - LAN Port (3m Ethernet cable) - Win 10 Desktop PC

Problem description:

• Only my PC loses connection and it is the only one connected by LAN/Ethernet to the AX86U
• Lights on router are all normal, and WiFi also works when my desktop loses connection
• The conncention can be lost both at wake up, i.e. i wake up PC and no connection, or during use
• Troubleshooting the network connection returns a DNS error
• Problem is resolved by rebooting PC

What should i keep an eye on when this happens? Log entries?
Any suggestions?

 

[bbunge]

Over the last couple of weeks my PC has started loosing connection to the internet. This has happened 4-5 times now, seemingly at random.

The problem started about at the same time as i updated my router to asuswrt 386_2 (stock asus firmware, now updated to 386_4) but it could be unrelated.
I don't know if its the router or my PC that's causing the problem and i hope that you guys can point me in the right direction.

My setup:

Cable Modem (Bridge mode) - Asus RT-AX86U - Ethernet - Win 10 Desktop PC

Problem description:

• Only my PC looses connection and it is the only one connected by LAN/ethernet to the AX86U
• The network icon in the systray/notification area displays a globe when the internet is lost
• Lights on router are all normal, and WiFi also works when my desktop looses connection
• The conncention can be lost both at wake up, i.e. i wake up PC and no connection, or during use
• Troubleshooting the network connection returns a DNS error (can't remember the exact wording)
• Problem is resolved by rebooting PC

What should i keep an eye on when this happens? Log entries?
Any suggestions?

I have noticed that Ethernet connections with my AX86U were showing in the log as connecting then disconnecting. Happened with a MAC Mini and a Dell Optiplex. Did not appear to cause any issues in my case. I did switch the Mini to WIFI and seldom use the Optiplex as I favor my new Lenevo Thinkbook with an AX200 card.
Just an hour ago I wiped the 386.2_4 and loaded up Asus 386.24840. So far I have not seen a log entry relating to Ethernet up then down over and over.
Will run the Asus firmware for a couple of days to see what happens.

 

[HTBruceM]

I have no idea if this would help you, but I had a bad punch block termination on a cat5e wall jack. It resulted in a high-resistance (but not completely OPEN) connection. This was an in-wall cable run of ~70ft or so (I think). To isolate the issue, I made a jig to short the wire pairs together on one end of the run, and measured the resistance at the other end. I saw something like 4 ohms on 3 of the shorted pairs, but 18-20 ohms on the "bad" pair. Since I didn't know which end was bad, I just cut the cable, put in a new RJ45 wall jacks on both ends with new terminations.

This was on the WAN side of my router, going through my house out to the FIOS ONT outside my garage. I kept getting internet connection drops that would reconnect after a few minutes. I was using an Orbi router which provided NO HELP AT ALL in it's logs. So I went double-NAT for a while with the ISP-provided router (Arris) ahead of the Orbi. Finally some help... the Arris logs contained entries that corresponded to my outages, and those entries always had a "link down" warning on the WAN port. At least the Arris gave me some breadcrumbs to follow.

 

[SoCalReviews]

Over the last couple of weeks my PC has started loosing connection to the internet. This has happened 4-5 times now, seemingly at random.

The problem started about at the same time as i updated my router to asuswrt 386_2 (stock asus firmware, now updated to 386_4) but it could be unrelated.
I don't know if its the router or my PC that's causing the problem and i hope that you guys can point me in the right direction.

My setup:

Cable Modem (Bridge mode) - Asus RT-AX86U - Ethernet - Win 10 Desktop PC

Problem description:

• Only my PC looses connection and it is the only one connected by LAN/ethernet to the AX86U
• The network icon in the systray/notification area displays a globe when the internet is lost
• Lights on router are all normal, and WiFi also works when my desktop looses connection
• The conncention can be lost both at wake up, i.e. i wake up PC and no connection, or during use
• Troubleshooting the network connection returns a DNS error (can't remember the exact wording)
• Problem is resolved by rebooting PC

What should i keep an eye on when this happens? Log entries?
Any suggestions?

Only my PC loses... LAN/Ethernet
The connection...

Just wanted to note few typos.

 

[HTBruceM]

Gotcha. My long winded story was leading towards checking your cabling between the PC and the network. It is CAT5 cable instead of CAT5E or CAT6? Are there any homemade connections between them?
I would also look into the Win10 System Event Log for any network events logged around the time of your outage. There will probably be some events there (since it lost internet connection)... try to look JUST PRIOR and see if there are any hints as to what's going on. You're left up to the whims of the ethernet driver developer and how much logging he decided to do.
The next thing I would try is to RESET the network in Windows 10.
After that I would try factory reset of the router.
If none of that does the trick, then try falling back to earlier router FW or Win10 ethernet drivers.
I'm out of suggestions after that.

 

[Damun]

Thanks for the suggestions @HTBruceM.

There are no homemade connections between the router and PC. Its just a 3m (10 feet) CAT6 cable.

I have been thinking of doing a network reset in Win 10. I just wanted to see if i could find the source of error before i did that.
Thanks.

 

[John Fitzgerald]

Thanks for the suggestions @HTBruceM.

There are no homemade connections between the router and PC. Its just a 3m (10 feet) CAT6 cable.

I have been thinking of doing a network reset in Win 10. I just wanted to see if i could find the source of error before i did that.
Thanks.

Do the Network Reset:
You can can try it this way,

Intel Support

Intel® Customer Support home page

support.killernetworking.com

 

[Damun]

So my PC just lost internet again. While i was surfing on the net.
Nothing in the windows system log. Can't access the Asus router.
Windows troubleshooter returns "no ethernet cable", despite the cable being in and both the notidication area icon says there is network and the LED is on on my Asus router. (The cable hasn't been touched for at least a month).
Restart solved the problem, as usual. Looked in the Asus log - nothing.

Did a network reset in Win 10 and everything is up and running.

Any suggestions to what could be causing this? Or where to look for logs or errors?

 

[HTBruceM]

My opinions follow. And they're definitely opinions.

"No network cable" means that your Windows NIC detected loss of ethernet link with the router AT SOME POINT. It no doubt recovered and regained the link. This is probably happening repeatedly and intermittently; and it manages to usually regain the link and then the network layers above may or may not recover. Intel NICs usually have sufficient logging that an issue like this would be logged in the Windows System Event Log; YMMV with other vendor NICs. In my opinion, here are the likely causes, in order of probability:

1) Bad/poor cable. It only needs one poor crimp that eventually loosened up over the years to the point of failure. Simply twisting/moving/touching the cable might provide enough force to temporarily re-establish a good crimp but it WILL eventually recur. I have also seen cases where a poor quality CAT6 cable picks up RF interference from nearby devices - such as power bricks, chargers, AC wiring, etc.
Just replace this cable.

2) A bad/failing NIC or driver in the PC. To isolate and workaround, can get a cheap $15 USB-NIC and see if the problem goes away. If it does, then the issue is with your NIC and/or driver.

3) A bad/failing port on the router. Try a different port. If this is the case, you will need to eventually replace the router.

As noted in my previous post, I had a failing crimp on a cable at a different point in my network (between the router WAN port and the ISP's modem/ONT). Very little logging/breadcrumbs were visible to help isolate the issue, until I found a different router that had more extensive debug mode logging than the Netgear router. And the log entries were similar to "No network cable"... it said "no link".

 

[Damun]

Thanks for the suggestions @HTBruceM.

I'll keep the suggestions in mind if/when the internet connection fails again.
Right now i'll wait and see if the network reset works.