[SOLVED] Intermittent network function - both ethernet and wifi

binkyd · 05-06-2023, 12:13 PM

Within an hour of connecting to the Internet, both wifi and ethernet suddenly fail, and a reboot is necessary. Sometimes this works for an hour or so, sometimes not.

Anything I can do here? It's a Lenovo Thinkcentre, but I don't have access to the windows-based hardware check anymore.

System: Kernel: 5.15.0-71-generic x86_64 bits: 64 compiler: N/A Desktop: Cinnamon 5.2.7
wm: muffin dm: LightDM Distro: Linux Mint 20.3 Una base: Ubuntu 20.04 focal

michaelk · 05-06-2023, 12:45 PM

It could be the router. Do you have problems with other devices?
What is its make and model number?

Since you have problems with both the easiest test would be to try a live version connected to the ethernet and see if the problem persists.

binkyd · 05-06-2023, 01:41 PM

The router (standard Telus Fibre) seems fine - 2 other units have no issues.

Live-USB also fails.

[Curiously, this is the second PC that's done this. A couple of years ago I had a big Dell that did the same thing (diff.residence). I do seem to have the Pauli Effect on calculators, ipod/mp3 players, and mobile phones - they always die within a couple of years, but will work after a while for other people.
So of course I'm wondering about this because of the similarity in problems.]

yvesjv · 05-06-2023, 02:21 PM

When it happens again, post the dmesg output.
As root in a shell try dmesg -W and wait

michaelk · 05-06-2023, 02:22 PM

With ethernet it could be a bad cable, bad ethernet adapter or some sort of OS, software, driver problem. Can you swap cables?

binkyd · 05-06-2023, 03:39 PM

For ethernet I swapped out for known-good cables to no avail. Even changed router ports. Tried a USB adapter to bypass the physical ETH port. Nope.
Don't know how to check the wifi.

First thing I did was run dmesg, and then after a reboot when it had internet, ran it again. There are quite a few differences; I don't know how to compare them except line by line, and that will take me a while. I don't know how to use meld to do it, or anything else.

Should I post both of them?

[Edit: just tried meld, made a mess

]

michaelk · 05-06-2023, 04:06 PM

Install ethtool if not already so
Find the name of the wired interface from the output of the command ip a and then run the command
sudo ethtool <interface name>

Check to make sure there the link is detected and that the speed is what is expected i.e 1000 Mb/s and the duplex is full. If for some reason the adapter auto-negotiation is not working or the connection is dropping out it might not match the other end. Check when it is working and when it is not.

binkyd · 05-06-2023, 04:56 PM

ethtool result identical both times - all in order it seems.

binkyd · 05-06-2023, 05:08 PM

Working thru dmesg

Before this point

Code:

[    0.960498]   with environment:
[    0.960499]     HOME=/
[    0.960500]     TERM=linux
[    0.960501]     BOOT_IMAGE=/boot/vmlinuz-5.15.0-71-generic

all's good, after things start to get quite different, and it's getting beyond me. Seems like stuff is happening in a different order, very confusing. Need a tool that's smarter than me, I do.

Any suggestions for a less-confusing way to compare these files?

btw - didn't post dmesg as it's about a thousand lines

GentleThotSeaMonkey · 05-06-2023, 07:47 PM

Try: https://github.com/UbuntuForums/wireless-info
It's a bit old, but hopefully still very useful.
You might collect a baseline when it's running ok, and then one when it's failed, but it may take quite a bit of digging through its tons of output. Or you can use cat ...|nc termbin.com 9999 to get a URL to post here.

More: by any chance, can you still ping the default gateway = the router, by numeric IP address?
If so, maybe it's this mess that I never figured out: https://www.linuxquestions.org/quest...1/#post6427544

wpeckham · 05-06-2023, 08:55 PM

The last time I saw a problem that looked like that I disabled NetworkManager and handled the networking manually. That worked, but I was never able to figure out WHY!

binkyd · 05-07-2023, 01:55 PM

Assuming this is a hardware issue, I've installed Phoronix Test Suite, but I'm being really dense about how to use it to test Networking function. Can't figure out the syntax cuz nothing works so far.
Found several how-tos but they're very bad. Can somebody direct me to some working examples of this?

business_kid · 05-07-2023, 02:13 PM

I wouldn't try Phoronix's test suite.

Diagnose. Divide and conquer. If both ethernet and wifi connect to the router, do they both vanish together? Does you box have an ip? If ethernet connects to the internet, turn off networkmanager and as root type

Code:

dhclient eth0

or 'dhcpcd eth0' If you're using sudo, they're probably in /sbin or /usr/sbin. If that works, stop fixing it before you break it.

If you're using some complicated network arrangement, enlighten us.

GentleThotSeaMonkey · 05-07-2023, 05:04 PM

Should we assume that, when it's down,
You have unsuccessfully tried pinging the router IP
And `ip r` reports absolutely nothing?

P. S. Thanks for the mention of https://www.phoronix-test-suite.com/
Sounds interesting! Now on my to-do list of things to play with

>"Curiously, this is the second PC that's done this..."
IF my FUD resolv.conf link is 'it',
This might be the 20,002nd PC to do this

binkyd · 05-07-2023, 06:46 PM

Oh, boy. This is embarrassing. Problem due to major brain fart.

Suddenly noticed that wi-fi and ethernet running at same time. Don't know when that happened, but Looked right at it a million times and never saw it.

Turned off wi-fi, now no issues with ethernet, and vice-cersa.

Apologies all, I'm going to hide under my bed for a while.