Re: Ethernet not active

Unplug the pi for a few minutes before rebooting?

It might be informative to report the state of the link lights next to the RJ45 port. If neither lights up it's likely a faulty connection, either in the Pi or the cable connectors.

Intermittents can take a long time to find, it's not a waste of time to keep written notes of what you've tried and what happened.

Good luck,

bob prohaska

try the ethtool and post back the result.

also interesting - is it configured with dynamic (dhcp) or with static config

I am fairly sure that is so low level an issue that it won't be software. That sounds like a dodgy cable or plug.

ethtool and ifconfig are good diagnostic tools. As are the lights on the ethernet interfaces

once there was some particle inside the RJ45 socket of the notebook which isolated one of the connectors and internet was not working

OP reported that same cable is working on another machine

yes indeed and it would tell us if the link is active and how it is configured

also there is nothing wrong to do something for the first time in your life - in this case executing ethtool command in the command line (Actually sudo ethtool)

BR

Am 23.09.2022 um 08:09:14 Uhr schrieb Deloptes:

This is unrelated until the ethernet link is established and the link LED lights up.

Not only that, but my understanding is that the link lights will light irrespective of any software opening the Ethernet port.

In short lack, of link lights means the cables or connector ports are faulty..

To light the Ethernet link lights, the physical driver part of the Ethernet chip (from MII to encoded Ethernet data) must be initialized, so some driver functions are needed.

Am 24.09.2022 um 13:04:55 Uhr schrieb The Natural Philosopher:

No, it is only relevant that both sides successfully established a link (it is called so). If the interface is "down" the link isn't possible, so the link LED will switch off. Also if there is a speed/duplex mismatch (NICs are set to a specific speed, but not the same), no link is there and the link LED won't light up permanently.

You can try out to set the link down with ip link set eth0 down

Then the hardware is fine, but the connection isn't active.

Oh dear. I am not able to run that command on my Ethernet switch. It doesn't understand TCP/IP at all.

Obviously it cannot be working at all.

Am 26.09.2022 um 08:23:12 Uhr schrieb The Natural Philosopher:

You can run it on Linux. On Windows you can reach that by disabling the network connection in ncpa.cpl.

Ethernet switches can also switch off ports. Cisco uses "shutdown" in the interface subcommand to reach that.

My switch has no command interface at all. I shut it down by disconnecting the power :=-)

Even a PC booted to its BIOS screen will light a link light on a switch. It certainly doesn't require an operating system

Am 26.09.2022 um 17:30:54 Uhr schrieb The Natural Philosopher:

A managed switch can be configured fi you like that possibility.

Most computers include an UEFI that supports networking (e.g. for network boot, Wake on LAN, firmware update etc.). This is the reason for that. There is a really small operating system like Intel Boot Agent that controls the NIC in that state.