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I'm using Ubuntu 18.04. Setting up my work PC to connect to the network and domain.

I've been working on switching to Netplan from using /etc/network/interfaces

I've created the yaml file and run

netplan generate
netplan apply

without any errors eventually. I've checked my config file located at /run/systemd/network for my interface, and it matches the correct details.

I've masked network-manager, and networking as I read that these can get in the way when using networkd.

The network runs fine, I can connect to the internet and to internal servers and ping / nslookup other servers. My issue is that after 5-10minues, I'm no longer able to ping other servers or nslookup other internal machines using their names, only IP. The name service seems to fail.

I then run

netplan apply

And it is fixed again! What is going on? Does anyone know a way to fix this permanently? I'm confident my yaml file is okay, but maybe something else is getting in the way or causing issues? I did think it may be network-manager, so I masked it.

I only have one yaml file located in /etc/netplan/01-network-card.yaml and it's format is:

network:
    version: 2
    renderer: networkd
    ethernets:
        eno1:
            dhcp4: false
            addresses: [ip.add.xx.xx/20]
            gateway4: xxx.xxx.xxx.x
            nameservers:
                search: [redacted.local]
                addresses: [xxx.xxx.xxx.xxx]
                addresses: [8.8.8.8]
        enp14s0:
            dhcp4: false 
            addresses: [xxx.xxx.xxx.xx/24]
            gateway4: xxx.xxx.xxx.x

Any ideas with this? Netplan is a pain. Also the connection enp14s0 is an admin connection to our network. I'm trying to configure eno1.

Thanks

Edit: thanks to commenters for help. Adding in extra info:

ls -al /etc/resolv.conf

lrwxrwxrwx 1 root root 39 May 24 16:48 /etc/resolv.conf -> ../run/systemd/resolve/stub-resolv.conf

cat /etc/resolv.conf

# This file is managed by man:systemd-resolved(8). Do not edit.
#
# This is a dynamic resolv.conf file for connecting local clients to the
# internal DNS stub resolver of systemd-resolved. This file lists all
# configured search domains.
#
# Run "systemd-resolve --status" to see details about the uplink DNS servers
# currently in use.
#
# Third party programs must not access this file directly, but only through the
# symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a different way,
# replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.

nameserver 127.0.0.53
options edns0
search redacted.local

Just as a note, the nameserver 127.0.0.53 is not one that I input into the netplan file - not sure where this comes from? imaginariumuk cat /etc/network/interfaces

# interfaces(5) file used by ifup(8) and ifdown(8)
#auto lo
#iface lo inet loopback

#auto eno1
#allow-hotplug eno1
#iface eno1 inet dhcp

Commented all the above out after attempting to switch to netplan.

systemd-resolve --status results before and after.

Global
          DNSSEC NTA: 10.in-addr.arpa
                      16.172.in-addr.arpa
                      168.192.in-addr.arpa
                      17.172.in-addr.arpa
                      18.172.in-addr.arpa
                      19.172.in-addr.arpa
                      20.172.in-addr.arpa
                      21.172.in-addr.arpa
                      22.172.in-addr.arpa
                      23.172.in-addr.arpa
                      24.172.in-addr.arpa
                      25.172.in-addr.arpa
                      26.172.in-addr.arpa
                      27.172.in-addr.arpa
                      28.172.in-addr.arpa
                      29.172.in-addr.arpa
                      30.172.in-addr.arpa
                      31.172.in-addr.arpa
                      corp
                      d.f.ip6.arpa
                      home
                      internal
                      intranet
                      lan
                      local
                      private
                      test

Link 3 (eno1)
      Current Scopes: DNS
       LLMNR setting: yes
MulticastDNS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
         DNS Servers: serverfromnetplan.240
                      8.8.8.8
          DNS Domain: redacted.local

Link 2 (enp14s0)
      Current Scopes: none
       LLMNR setting: yes
  • Is this a desktop or server installation? Why netplan instead of NM? Why /20 on en01? I hate it when users redact address information that could be helpful in solving the problem :-( Edit your question and show me ls -al /etc/resolv.conf and cat /etc/resolv.conf and cat /etc/network/interfaces. – heynnema May 30 at 16:15
  • Did you also stop network manager when masking it? – slangasek May 31 at 0:54
  • What is the output of systemd-resolve --status before and after you stop being able to resolve names? – slangasek May 31 at 1:16
  • Thanks for the comments. I'm testing switching over to Netplan at work, that's why I have redacted info, I don't really want to share work network info. – AlexG42 May 31 at 7:51
  • Sorry forgot to mention, it is a desktop. – AlexG42 May 31 at 9:07

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