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Not sure what I'm missing here, but when I am installing Ubuntu Server 18.04.1 LTS (Bionic Beaver) the system can't seem to connect to the router, I keep getting the error message saying that no network has been found - Yet, the system is hard wired into the network and is showing up when I view the admin settings on the router, the server is showing up.

What else can I try to get the system connected so Ubuntu can be installed?

The fact that the system is showing up on the router settings is strange that the server can't seem to find a connection and keeps telling me that DHCP may not be enabled on the router.

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  • Is it possible that DNS is not being set somehow? Sep 10, 2018 at 21:43
  • @JustinPearce Everything is always possible - but how? In this specific scenario, I've had multiple devices hard wired to the identical port previously that have never had a problem connecting directly to the internet. Not sure how I'd even go about debugging this one...any ideas? Sep 10, 2018 at 22:19

1 Answer 1

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(many of the following commands will need to run with superuser privileges i.e. execute directly as root or prepend the command with sudo)

  • As far as I know Ubuntu 18 uses systemd / networkd for network configuration, start with:

    networkctl status 
    journalctl -b -u systemd-networkd 
    

Other basic Linux wired network diagnostics include:

  • Check if all expected network interfaces have been detected by the OS and drivers are loaded:

    lspci                   
    lsusb 
    ifconfig -a 
    dmesg  ( |grep eth )
    
  • Check if the cables are connected, a link is detected, correct network speeds are negotiated/set:

    ip link 
    ethtool <interface_name> 
    
  • Check if your OS is configured to automatically start network the interfaces at boot. How that is configured differs between Linux distributions and releases:

    • For Debian based distributions such as Ubuntu: /etc/network/interfaces should have lines starting with keyword auto

    • For Red Hat Enterprise Linux derived distributions, RHEL, CentOS, Fedora /etc/sysconfig/network-scripts/ifcfg-<interface_name> should probably contain a keyword ONBOOT="yes"

  • Those files will also show if the NIC's are configured with a static ip-address or if they should be configured automatically with DHCP.

  • Check if any and the correct IP-addresses and subnet masks are assigned to your network interface card(s):

    ip addr
    ifconfig -a 
    
  • Check routing, confirm that a route to 0.0.0.0 and/or a default gateway are present

    ip route 
    netstat -rn 
    route 
    
  • Can the default gateway be reached:

    ping <ip-address_of_default_gw> 
    

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