[CentOS] RTL8111/8168B always 100mbps

John Doe wrote:
> From: Muhammad Panji <sumodirjo at gmail.com>
>
>> I have an onboard Realtek RTL8111/8168B NIC. from lspci -vv :
>> 02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
>> RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 02)
>> It is detected, but why the speed is always 100Mbps, already change
<snip>
> I tried:
> # ethtool -s eth0 speed 1000 duplex full autoneg off advertise 0x020
> but auto-negotiation stays on and I only get 100Mbps...
>
> I tried:
> # ethtool -s eth0 duplex full autoneg off advertise 0x020
> auto-negotiation is off but nothing change...

I was working on a similar problem (turned out to be our network switch),
but *did* find that order of the ethtool command is significant: you
*MUST* have autoneg off as the first parameter; that is, try
# ethtool -s eth0  autoneg off speed 1000 duplex full advertise 0x020

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