Outgoing internet died on containers - Ubuntu 20.04 - Snap LXD

So the title says it all. I’ve been using LXD for years now - happily. Today I logged into a container and wanted to check if there are any updates. And the apt update simply failed, saying no internet. Uh-oh.

The host is a dedicated server at Hetzner, with one IPv4 by default, and 1x additional IP.
OS: Ubuntu 20.04

The only things I can think of:

  • I added this to my /etc/sysctl.conf file like 2 days ago:

The reason being is that I had Mailcow and Apache on the same machine and Apache did not want to start otherwise on boot. Once system booted, I could start it by hand. Since then I have removed those lines of course, thinking those were causing the no internet in LXD.

  • APT or Snap updated something that broke things.
    I’ve tried looking in logs but could not see anything relevant.

Please, let me know what logs should I include.

tracking:     4.0/stable
refresh-date: 14 days ago, at 20:32 CET
root@y ~ # uname -a
Linux y 5.4.0-91-generic #102-Ubuntu SMP Fri Nov 5 16:31:28 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
root@y ~ # lxc network show lxdbr0
  ipv4.nat: "true"
  ipv6.address: fd42:7557:57a7:1fdc::1/64
  ipv6.nat: "true"
description: ""
name: lxdbr0
type: bridge
- /1.0/instances/custom-cast
- /1.0/instances/machine1
- /1.0/profiles/default
managed: true
status: Created
- none
root@y ~ # lxc config show machine1
architecture: x86_64
  boot.autostart: "true"
  image.architecture: amd64
  image.description: ubuntu 20.04 LTS amd64 (release) (20201210)
  image.label: release
  image.os: ubuntu
  image.release: focal
  image.serial: "20201210"
  image.type: squashfs
  image.version: "20.04"
  limits.memory: 100%
  limits.memory.enforce: hard
  limits.memory.swap: "true"
  volatile.base_image: e0c3495ffd489748aa5151628fa56619e6143958f041223cb4970731ef939cb6
  volatile.eth0.host_name: veth872eb534
  volatile.eth0.hwaddr: 00:16:3e:6c:41:87
  volatile.idmap.base: "0"
  volatile.idmap.current: '[{"Isuid":true,"Isgid":false,"Hostid":1000000,"Nsid":0,"Maprange":1000000000},{"Isuid":false,"Isgid":true,"Hostid":1000000,"Nsid":0,"Maprange":1000000000}]'
  volatile.idmap.next: '[{"Isuid":true,"Isgid":false,"Hostid":1000000,"Nsid":0,"Maprange":1000000000},{"Isuid":false,"Isgid":true,"Hostid":1000000,"Nsid":0,"Maprange":1000000000}]'
  volatile.last_state.idmap: '[{"Isuid":true,"Isgid":false,"Hostid":1000000,"Nsid":0,"Maprange":1000000000},{"Isuid":false,"Isgid":true,"Hostid":1000000,"Nsid":0,"Maprange":1000000000}]'
  volatile.last_state.power: RUNNING
  volatile.uuid: 0b05f754-e7d5-4180-8a4e-a750729f062d
    connect: tcp:
    listen: tcp:
    type: proxy
ephemeral: false
- default
stateful: false
description: ""