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Topic: eth0 is down on laptop after reboot on battery  (Read 601 times) previous topic - next topic
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eth0 is down on laptop after reboot on battery

ethernet is blocked by tlp when laptop uses battery. For power saving.
tlp.conf has no dedicated option to on/off ethernet as it does for wifi, nfc, bluetooth. 
It is reasonably suggested - why you don't plug in charger when you can plug wired connection?
To make life easier for a user there is no even mention about disabling ethernet in config file.
Sometimes such approach can add complexity.

If user wants to control manually ethernet or any other PCI device regardless of AC/battery there is an option.
Find PCI device address with
Quote
lspci
Exclude device addresses from power management in /etc/tlp.conf
Quote
RUNTIME_PM_DENYLIST="01:00.0"

https://linrunner.de/tlp/settings/runtimepm.html#runtime-pm-denylist

But this option currently does not work and it needs kernel or tlp fix.

------------------------------
I use runit.
 Often after reboot
ip a - shows eth0 state DOWN
There is no ping to router.

After
Quote
ip link set eth0 down
ip link set eth0 up
network appears.

Can tlp optimization for laptop cause the problem?
How to configure tlp to let eth0 up on boot?

Re: Dynamic configuration for dhcpcd

Reply #1 –
If your network interface accidentally goes down, dhcpcd is nothing to do with that. The DHCP client daemon does not establish physical (layer 2) network connection, it uses existing connections. This is probably an issue with network misconfiguration either on your PC or your router. It could also be a hardware issue, again, either on your PC or your router.

Re: Dynamic configuration for dhcpcd

Reply #2 –
Network is down only after reboot or poweroff. It does not dissapeares during use.

Re: Dynamic configuration for dhcpcd

Reply #3 –
I don't get exactly what is happening.

If your Ethernet interface is down after booting up, then, again, it's either network misconfiguration or hardware issue. DNS settings are applied either on a router side (and then transferred to a PC via DHCP) or directly on your PC.

If your computer obtains IP configuration via DHCP, and after that you can't ping your router, then it's highly likely that something is wrong with the router, that's why it doesn't respond.

Try another router, if it's available. It's hard to say remotely what exactly is going on, but it seems to me that your router probably meets its decline.

Re: Dynamic configuration for dhcpcd

Reply #4 –
deleted wrong suggestions

Re: Dynamic configuration for dhcpcd

Reply #5 –
I booted with SystemrescueCD network works.
Booted back to artix - no ping to router.

Quote
ip link set eth0 down
ip link set eth0 up

Enables connection to router. But with delay.
Network is down after reboot.

Re: Network is down after reboot.

Reply #6 –
Can tlp disable lan?
It seems network does not start up on boot when laptop uses battery.

Removed tlp - now eth0 is up on boot.
But now problem with rfkill blocking wifi must back.

Checked few times with enabled/desabled tlp in config file.

Looks like developers disabled wired interface for battery saving.
But didn't add option in config to enable it manually.
There should be option to enable eth0 on battery boot in config.