Ethernet not working after removing GPU

Question

So, I am having an issue where my Ubuntu Server (v18.04.3) no longer wants to connect to the internet. It was working fine before I took out my gpu to sell. I have googled to my hearts content and have found many people with the same or similar issues. I have tried all the remedies that have been suggested, but to no avail. Could someone give me a bite more insight as to how I might fix this?

Links I have tried:

• Why is my ethernet interface called enp0s10 instead of eth0?
• https://www.freedesktop.org/software/systemd/man/systemd.net-naming-scheme.html
• Wrong predictable network interface name in Debian
• https://askubuntu.com/questions/826325/how-to-revert-usb-wifi-interface-name-from-wlxxxxxxxxxxxxx-to-wlanx/826614#826614
• Internet not working without gpu installed?

Outputs from commonly asked commands:

• ifconfig

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
        inet 127.0.0.1 netmask 255.0.0.0
        inet6 ::1 prefixlen 128 scopeid 0x10<host>
        loop txqueuelen 1000 (Local Loopback)
        RX packets 2160 bytes 154368 (154.3 KB)
        RX errors 0 dropped 0 overruns 0 frame 0
        TX packets 2160 bytes 154368 (154.3 KB)
        TX errors 0 dropped 0 overruns 0 carrier 0 collisions0

• ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_left forever
    inet ::1/128 scope host
       valid_lft forever preffered_left forever
2: enp6s0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether d8:cb:8a:bf:3c:af brd ff:ff:ff:ff:ff:ff

EDIT: Spelling/grammar

Answer 1

When you removed the GPU, the PCIe bus configuration of your system changed, causing the bus location of your NIC to change. This change is reflected in the PCI IDs in the lspci listing, and also in the "predictable network interface names".

Your NIC used to be named something like enp?s0; now it is enp6s0.

Edit the netplan YAML file to change the name of the NIC to match what it is now:

sudo nano /etc/netplan/*.yaml

Change enp?s0 (where ? is some number unknown to me) to enp6s0 and press Ctrl+X to save & exit.

(Based on your comments, perhaps you have already done this.)

Then run sudo netplan apply. (This might be the only thing you're missing.)

Answer 2

When you removed the GPU, the PCIe bus configuration of your system changed, causing the bus location of your NIC to change. This change is reflected in the PCI IDs in the lspci listing, and also in the "predictable network interface names".

Your NIC used to be named something like enp?s0; now it is enp6s0.

So what if I don't have the netplan command available?

networkctl will be available on most Linux distros. The command below will give you the current link being used (ether in this case).

# networkctl list

IDX LINK             TYPE               OPERATIONAL SETUP     
  1 lo               loopback           n/a         unmanaged 
  2 enp5s0           ether              n/a         unmanaged 

The enp5s0 value in this example is the new link that will need to replace enp6s0 in the configuration below.

# cat /etc/network/interfaces
auto lo
iface lo inet loopback

iface enp6s0 inet manual

Note: You will want to change all instances of enp6s0 in this file.

Once that is change is written, restart your networking and the link should be online.