Linux Mint drops ethernet connection on one switch but not on another

Valmond

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Hello!

I have a Linux box with Linux Mint installed that runs some network programs, I also have two switches in my LAN, one in my "office" (bedroom) and one in a cupboard...

If I connect (over ethernet) the Linux Mint box to the first one, it will be online forever. I can ping it, use VNC (I have a fake display plug) to connect to it etc. but it is sitting in my bedroom, making noise and heat.

If I move the box to the cupboard and connect to the second switch (also over ethernet), the connection drops after some hours (maybe half a day or a day or so).

If I just de-connect the ethernet cable and plug it back in to the switch, the connection comes back on.

I also have a Synology NAS on the "cupboard" switch, and it has no de-connection problems what so ever.

Both the switches are on the same subnet.

I just don't know what to do, any idea how to fix this or what to even search for?

Cheers !

Valmond
 


Hello @Valmond,
Welcome to the Linux.org forum.
I think that you will have to assume it's something in the switch that is shutting down your connection. I'm no expert on ethernet connections. But Is there a power save function on the switch? It may help other to know more about your machine.
Please go to a terminal and type the following command and post the results here.
Code:
inxi -Fxxzr
Some things you could try.
swap the switches see if you experience the same behavior. Check all the connections make sure they are all solid. Check the cables make sure they are all good. plug the machine into a different port if available. It is unlikely to be a problem with Mint as it work well with the other switch.
I'm sure someone more knowledgeable will be along to help, but those are good first steps.
 
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I concur with kc1di, if it works fine on one switch and not the other you have done all your diagnostic work and the problem lies in the switch. or at least external to the PC. switches are very cheap so replace it if you must or as was mentioned plug into a different port. However if you have a dead port on a switch it is time to replace it.
 
We need Ethernet because wifi isn't always reliable. Whats next... drop USB support
 
Thanks!

I changed the switch for another switch, same problem... I will try with "the switch that works" (but it's in use so I have to fiddle a bit)


Here is the output from inxi :

Cheers

System:
Kernel: 5.15.0-56-generic x86_64 bits: 64 compiler: gcc v: 11.3.0
Desktop: Cinnamon 5.4.12 tk: GTK 3.24.33 wm: Mutter dm: LightDM
Distro: Linux Mint 21 Vanessa base: Ubuntu 22.04 jammy
Machine:
Type: Laptop System: Dell product: OptiPlex 9020 v: 01
serial: <superuser required> Chassis: type: 16 serial: <superuser required>
Mobo: Dell model: 0KC9NP v: A01 serial: <superuser required> BIOS: Dell
v: A12 date: 05/06/2015
CPU:
Info: quad core model: Intel Core i5-4690S bits: 64 type: MCP arch: Haswell
rev: 3 cache: L1: 256 KiB L2: 1024 KiB L3: 6 MiB
Speed (MHz): avg: 2387 high: 3220 min/max: 800/3900 cores: 1: 1996
2: 1996 3: 2338 4: 3220 bogomips: 25539
Flags: avx avx2 ht lm nx pae sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx
Graphics:
Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics
vendor: Dell driver: i915 v: kernel ports: active: HDMI-A-2
empty: DP-1, DP-2, HDMI-A-1, VGA-1 bus-ID: 00:02.0 chip-ID: 8086:0412
Display: x11 server: X.Org v: 1.21.1.3 driver: X: loaded: modesetting
unloaded: fbdev,vesa gpu: i915 display-ID: :0 screens: 1
Screen-1: 0 s-res: 1920x1080 s-dpi: 96
Monitor-1: HDMI-2 mapped: HDMI-A-2 model: DP1080P60 res: 1920x1080
dpi: 102 diag: 595mm (23.4")
OpenGL: renderer: Mesa Intel HD Graphics 4600 (HSW GT2)
v: 4.6 Mesa 22.0.5 compat-v: 3.1 direct render: Yes
Audio:
Device-1: Intel Xeon E3-1200 v3/4th Gen Core Processor HD Audio
vendor: Dell driver: snd_hda_intel v: kernel bus-ID: 00:03.0
chip-ID: 8086:0c0c
Device-2: Intel 8 Series/C220 Series High Definition Audio vendor: Dell
driver: snd_hda_intel v: kernel bus-ID: 00:1b.0 chip-ID: 8086:8c20
Sound Server-1: ALSA v: k5.15.0-56-generic running: yes
Sound Server-2: PulseAudio v: 15.99.1 running: yes
Sound Server-3: PipeWire v: 0.3.48 running: yes
Network:
Device-1: Intel Ethernet I217-LM vendor: Dell driver: e1000e v: kernel
port: f080 bus-ID: 00:19.0 chip-ID: 8086:153a
IF: eno1 state: up speed: 1000 Mbps duplex: full mac: <filter>
RAID:
Hardware-1: Intel SATA Controller [RAID mode] driver: ahci v: 3.0
bus-ID: 00:1f.2 chip-ID: 8086:2822
Drives:
Local Storage: total: 111.79 GiB used: 80.5 GiB (72.0%)
ID-1: /dev/sda vendor: Crucial model: CT120BX500SSD1 size: 111.79 GiB
speed: 6.0 Gb/s serial: <filter>
Partition:
ID-1: / size: 109.47 GiB used: 80.5 GiB (73.5%) fs: ext4 dev: /dev/sda1
Swap:
ID-1: swap-1 type: file size: 2 GiB used: 1.5 MiB (0.1%) priority: -2
file: /swapfile
Sensors:
System Temperatures: cpu: 61.0 C mobo: 27.8 C
Fan Speeds (RPM): N/A
Repos:
Packages: 2961 apt: 2941 flatpak: 20
No active apt repos in: /etc/apt/sources.list
Active apt repos in: /etc/apt/sources.list.d/official-package-repositories.list
1: deb http://packages.linuxmint.com vanessa main upstream import backport
2: deb http://archive.ubuntu.com/ubuntu jammy main restricted universe multiverse
3: deb http://archive.ubuntu.com/ubuntu jammy-updates main restricted universe multiverse
4: deb http://archive.ubuntu.com/ubuntu jammy-backports main restricted universe multiverse
5: deb http://security.ubuntu.com/ubuntu/ jammy-security main restricted universe multiverse
Info:
Processes: 198 Uptime: 10d 3h 15m Memory: 7.67 GiB used: 5.64 GiB (73.6%)
Init: systemd v: 249 runlevel: 5 Compilers: gcc: 11.3.0 alt: 11/7/8/9
Shell: Bash v: 5.1.16 running-in: gnome-terminal inxi: 3.3.13
 
I assume that these are cheap unmanaged consumer Ethernet switches with no user software controls or physical buttons. In other words, the simple Ethernet switches that everyone uses in their homes.

How is the network arranged? Does each switch have its own direct connection to the router, or could you have switches plugged into switches in a tree/branch arrangement? If so, to how many levels?

In the bad old days, different hubs and switches would behave in a flaky manner when you started plugging switches together to create additional Ethernet ports in a room with a single jack or simply needed more ports. We learned in our labs that some switches handled this situation better than other switches, and some switches were downright uncooperative even one level down.

Furthermore, some of those switches had a specially marked Ethernet port which was supposed to be used if you plugged another hub or switch into it, or you could use it for any device. You were not supposed to plug another switch into the other "regular" ports. I never knew why or what made those ports different, but that's how they were marked and I followed the directions. Perhaps the port was not special, but marked that way to discourage users from connecting more than one downstream switch. It was always the last physical port on the switch. To this day I connect downstream switches to the last port on the upstream switch; an acquired habit. Maybe it had something to do with hub vs. switch.
-> If nothing else works, try connecting the downstream switches to the highest port on the upstream switches. It can't hurt.

The Synology device does network backups and might have large data bursts. Could it be overloading the capacity of one of the switches when it is running multiple backups at the same time and the network is also being used for other things?

I have not worried about such switch reliability issues for a long time, but one of those thoughts may explain what is happening here. If it were my problem, I would start a notebook and keep careful records. Make one change at a time and retest between changes. I would start by swapping cable positions around at each step of the network path and confirm that it isn't just a defective port on one of the switches. Remember to test with the upstream switches even though they may not seem involved. Next, replace the switches one at a time to confirm you do not have a defective switch or defective port on a switch. Troubleshoot the problem systematically.

In case it matters, I have three layers of switches at my home. It would normally be two layers: a large switch in the closet connected to the router, and a few smaller switches in rooms that need additional Ethernet ports. (The reason for three layers is that I am playing with VLANs. My partner wants to add a doorbell/camera and we have other appliances. I won't put them on our network unless they are isolated from our regular LAN. The main point is that our network is operating at three layers without issues.)
 
Thank you, that was it, shaky flaky switches all the way down :)

So I just got myself a wifi dongle (and an usb extension cable, as the key didn't like to be too close to the metal) and I have a snappy 16Mb link which for now (I will cable it one day) is enough for me.
 

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