I've build my detain 11 home-server with a gigabyte b550 gaming x motherboard. On that board there is a realtek RTL8111/8168/8411 Lan chip. At home I've everywhere cat 6A cables and everywhere I can make use of my 1000Mb/s internet speed.

But when I connect my server to the ethernet, the speedtest says I have an internet speed of +/- 95 Mb/s. Even when I use the same internet cable as my windows computer, that normally has a speed of +/- 800 Mb/s.

It looks like that the speed is restricted at 100Mb/s.

I've tried to install the driver with install firmware-realtek and from realtek directly.

sudo apt-get list firmware-realtek

I've already did some Googling and this is not a new issue. But I'm unable to find any solution. One person sad that I should run this command. But after that command my server was unable to connect to the network.

sudo ethtool -s enp4s0 speed 1000 duplex full autoneg on

ethtool settings:

Settings for enp4s0:
    Supported ports: [ TP    MII ]
    Supported link modes:   10baseT/Half 10baseT/Full
                            100baseT/Half 100baseT/Full
    Supported pause frame use: Symmetric Receive-only
    Supports auto-negotiation: Yes
    Supported FEC modes: Not reported
    Advertised link modes:  10baseT/Half 10baseT/Full
                            100baseT/Half 100baseT/Full
    Advertised pause frame use: Symmetric Receive-only
    Advertised auto-negotiation: Yes
    Advertised FEC modes: Not reported
    Link partner advertised link modes:  10baseT/Half 10baseT/Full
                                         100baseT/Half 100baseT/Full
    Link partner advertised pause frame use: Symmetric Receive-only
    Link partner advertised auto-negotiation: Yes
    Link partner advertised FEC modes: Not reported
    Speed: 100Mb/s
    Duplex: Full
    Auto-negotiation: on
    master-slave cfg: preferred slave
    master-slave status: slave
    Port: Twisted Pair
    PHYAD: 0
    Transceiver: external
    MDI-X: Unknown
    Supports Wake-on: pumbg
    Wake-on: d
    Link detected: yes
04:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8111/8168/8411 PCI Express Gigabit Ethernet Controller [10ec:8168] (rev 16)

Do people maybe have a clue how I can fix this?

  • 1
    The speed test is usually testing between your home system and some external server, right? The network that your network provider provides to you, what speed is it? Are you paying for gigabit ethernet?
    – Kusalananda
    Jun 23 at 22:26
  • Yes, I’m paying for gigabit Ethernet. All of my devices have a Ethernet speed of around 800mbps. Jun 24 at 5:37
  • 1
    Could you clarify between what devices exactly you are seeing speeds of about 95 Mbit/s?
    – Kusalananda
    Jun 24 at 5:41
  • OK, ethtool says the speed of your link has been negotiated to 100Mb/s, so this is really something between your motherboard and what is attached directly at the other end of the cable. What is that? Jun 24 at 7:21
  • I get a speed at 95Mbit/s during the speedtest. I've my server connected via a cable to a linksys mx5300 that act like an access point. The linksys mx5300 is connected via the cable to my ISP router (KPN V12 router). Both are capable of 1Gb/s. Jun 24 at 7:41


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