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I've followed the highest voted answer by heynnema on this Linux Ubuntu Server 20.04 LTS: 'Network Unreachable' question on netplan:

  1. Changed /etc/netplan/'01-network-manager-all.yml content to
  network:
      version: 2
      renderer: networkd
      ethernets:
        enp4s0:
          addresses:
            - 192.168.1.200/24
          gateway4: 192.168.1.254
          nameservers:
            addresses:
              - 8.8.8.8
              - 8.8.4.4
  1. ran following commands
sudo netplan generate
    
sudo netplan apply
    
reboot # mandatory

and am now cut off from the internet on that machine. I had made a copy of the original '01-network-manager-all.yml' file and ran the commands specified in the answer again on that,

sudo netplan generate

sudo netplan apply

reboot # mandatory

but to no success. How can I undo those netplan changes?

Edit:

ip a output:

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_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: wlp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 5c:ba:ef:cd:c6:19 brd ff:ff:ff:ff:ff:ff
    inet 192.168.30.19/24 brd 192.168.30.255 scope global dynamic noprefixroute wlp1s0
       valid_lft 604268sec preferred_lft 604268sec
    inet6 fe80::44ae:37a2:66c5:b8ce/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
3: lxcbr0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default qlen 1000
    link/ether 00:16:3e:00:00:00 brd ff:ff:ff:ff:ff:ff
    inet 10.0.3.1/24 brd 10.0.3.255 scope global lxcbr0
       valid_lft forever preferred_lft forever
4: br-bd526d132fb7: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default 
    link/ether 02:42:24:07:b4:a3 brd ff:ff:ff:ff:ff:ff
    inet 172.18.0.1/16 brd 172.18.255.255 scope global br-bd526d132fb7
       valid_lft forever preferred_lft forever
    inet6 fe80::42:24ff:fe07:b4a3/64 scope link 
       valid_lft forever preferred_lft forever
5: docker0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN group default 
    link/ether 02:42:fd:ac:22:cc brd ff:ff:ff:ff:ff:ff
    inet 172.17.0.1/16 brd 172.17.255.255 scope global docker0
       valid_lft forever preferred_lft forever
7: vethc2e94a7@if6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue master br-bd526d132fb7 state UP group default 
    link/ether 1e:00:18:36:2a:c7 brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet6 fe80::1c00:18ff:fe36:2ac7/64 scope link 
       valid_lft forever preferred_lft forever
user_90809
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  • Is this Ubuntu Desktop or Server installation? Is that your correct gateway address? – mpboden May 07 '23 at 19:13
  • Ubuntu Desktop Installation and the gateway address was wrong as I just found out, but changing it, executing the commands and rebooting did not fix the problem. – user_90809 May 07 '23 at 19:38
  • If it’s a Desktop installation, change the renderer line to `renderer: NetworkManager`. The desktop install doesn’t use `networkd` – mpboden May 07 '23 at 19:49
  • Done. The issue unfortunately is still there. – user_90809 May 07 '23 at 19:57
  • I just don't know why reverting to the original file content does not fix the network connection. – user_90809 May 07 '23 at 19:59
  • The Desktop installation uses whichever backend you configure it to use. – slangasek May 07 '23 at 21:28
  • Why are you using static networking instead of DHCP? – slangasek May 07 '23 at 21:29
  • Please update your question to include the output if `ip a`. – mpboden May 07 '23 at 22:03
  • @slangasek True…Desktop can use `networkd`. I misspoke. But by default, Desktop is using Network Manager. So if OP wants to use `networkd`, then they’d have to stop, disable, and mask Network Manager service. Then unmask, enable, and start `systemd-networkd` service. I made an assumption that this hasn’t been done. – mpboden May 07 '23 at 22:16
  • You can choose whichever (`networkd` vs. `NetworkManager`) you prefer, but we strongly recommend NetworkManager for desktop users unfamiliar with the details of networking. `netplan` will set up your network *exactly* the way you specify, even if your specification is wrong. – user535733 May 08 '23 at 00:42
  • @user535733 And how do I revert to NetworkManager? My 01-network-manager-all.yaml file in /etc/netplan/ contains the original file content and I tried to do exactly that. – user_90809 May 08 '23 at 07:32
  • @mpboden I want to revert back to the original NetworkManager solution. I don't want to use networkd. Will update my question with ip a output. – user_90809 May 08 '23 at 07:37
  • Your new YAML file is setting up a static IP on the `enp4s0` interface, but the output of `ip a` indicates that you don’t have an interface of that ID. So I would start by deleting the YAML file you created and restore the original so that there is only one YAML file in the `/etc/Netplan` directory. – mpboden May 08 '23 at 16:53
  • @mpboden That's what I did when I noticed the internet connection was gone, which didn't help. – user_90809 May 09 '23 at 07:36

0 Answers0