RPi 3B+: Configure NIC to 100baseT/Full manually?

Help and Support
1

Hi there,

I upgraded my Raspberry to the current model 3B+, but I only have a 2-pair wired network connection with 100MBit. Unfortunately, auto negotiation does not work and my brandnew RPi does not have a network connection at all. If I configure the NIC manually with ethtool (sudo ethtool -s eth0 speed 100 duplex full autoneg off) I get a link and a network connection.

Is there an elegant way to configure the lan adapter permanently to 100baseT/Full that I have a network connection even after a restart/reboot?

Thanks for your thoughts!

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2

Either edit /etc/network/if-pre-up.d/ethtool to test for eth0 and set it correctly, or add another file in that directory that does it.

3

Thanks for you answer, nabsltd. But what do you mean with “test for eth0”?

4

You don’t want to apply that change to every interface (like the loopback, or WiFi), so you’d add something like this to the existing “ethtool” file

if [ "$IFACE" == "eth0" ]
then
    SETTINGS="$SETTINGS speed 100 duplex full autoneg off"
fi

Put those lines right before the last line in the “ethtool” file and it should work.

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