[SOLVED] Unstable LAN at a PC; HowTo solve?

floppy_stuttgart · 07-27-2022, 04:43 AM

Hello,
on the same Netgear LAN-splitter, I have 2 PCs.
One is fine (Win machine; notebook; connected to an external server via VPN).
The other is showing instability and I had to change to WLAN (connection to home router).
Preferably I would go back to LAN.
Few data of the PC are below.
Any hint is welcome (no urgency, it works with wlan).

Debian11, 5.10.0-16-amd64

dmesg

Quote:

[ 218.369536] e1000e 0000:00:1f.6 eno1: NIC Link is Down
[ 225.403323] e1000e 0000:00:1f.6 eno1: NIC Link is Up 100 Mbps Half Duplex, Flow Control: Rx/Tx
[ 225.403325] e1000e 0000:00:1f.6 eno1: 10/100 speed: disabling TSO
[ 225.405427] e1000e 0000:00:1f.6 eno1: NIC Link is Down
[ 227.100608] e1000e 0000:00:1f.6 eno1: NIC Link is Up 100 Mbps Full Duplex, Flow Control: None
[ 227.100609] e1000e 0000:00:1f.6 eno1: 10/100 speed: disabling TSO
[ 324.777492] e1000e 0000:00:1f.6 eno1: NIC Link is Down
[ 358.358721] e1000e 0000:00:1f.6 eno1: NIC Link is Up 100 Mbps Full Duplex, Flow Control: None
[ 358.358727] e1000e 0000:00:1f.6 eno1: 10/100 speed: disabling TSO
[ 358.482215] e1000e 0000:00:1f.6 eno1: NIC Link is Down
[ 363.329978] e1000e 0000:00:1f.6 eno1: NIC Link is Up 100 Mbps Full Duplex, Flow Control: None
[ 363.329979] e1000e 0000:00:1f.6 eno1: 10/100 speed: disabling TSO

from lspci -v

Quote:

00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection (7) I219-LM (rev 10)
DeviceName: Onboard Lan
Subsystem: Hewlett-Packard Company Ethernet Connection (7) I219-LM
Flags: bus master, fast devsel, latency 0, IRQ 125, IOMMU group 9
Memory at f0500000 (32-bit, non-prefetchable) [size=128K]
Capabilities: [c8] Power Management version 3
Capabilities: [d0] MSI: Enable+ Count=1/1 Maskable- 64bit+
Kernel driver in use: e1000e
Kernel modules: e1000e

TenTenths · 07-27-2022, 05:05 AM

From your dmsg output it looks like there's flapping in the auto-negotiation for the link connection.

You don't specifically mention the distribution, so check on the relevant documentation to disable auto-negotiate and see if that gives you any better stability.

michaelk · 07-27-2022, 06:49 AM

Individual ports and adapters can fail. Try switching to another port to see if the problem goes away. If it doesn't it may be a bad network adapter, if it does it is the switch.

floppy_stuttgart · 07-30-2022, 08:05 AM

For the reason I have the LAN around the house with electricity network adaptors, I had a look again at this.
Instead of putting the PC LAN adaptor into the connector of a 6m cable (stored on the floor with loops), it is now after a 2m straight cable going to the electricity connector in the wall.
The PC started and the internet came straight.
It works stable.
Topic closed.