Thank you very much for providing the additional information. I can now reproduce the issue in a stock ubuntu-24.04.1-live-server-amd64.iso installation. => After "apt install ubuntu-desktop-minimal" the primary ethernet interface is listed as "enp1s0 ethernet unmanaged --" by NetworkManager ("nmcli d"), which is expected, as "netplan apply" was not run, yet. BUT: It's also listed as unmanaged by systemd-networkd ("networkctl"), therefore dropped it's DNS configuration from "resolvectl".
I think I've found an even smaller reproducer: $ lxc launch ubuntu-daily:noble nn-lp2097769-desktop-dns $ lxc shell nn-lp2097769-desktop-dns root@nn-lp2097769-desktop-dns:~# networkctl IDX LINK TYPE OPERATIONAL SETUP 1 lo loopback carrier unmanaged 307 eth0 ether routable configured 11 links listed. root@nn-lp2097769-desktop-dns:~# resolvectl Global Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported resolv.conf mode: stub Link 307 (eth0) Current Scopes: DNS Protocols: +DefaultRoute -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported Current DNS Server: 10.238.94.1 DNS Servers: 10.238.94.1 fd42:7213:f20e:bd74::1 fe80::216:3eff:fe0f:ee29 DNS Domain: lxd root@nn-lp2097769-desktop-dns:~# apt install ubuntu-settings network-manager [...] # still OK root@nn-lp2097769-desktop-dns:~# nmcli d DEVICE TYPE STATE CONNECTION eth0 ethernet connected (externally) eth0 lo loopback connected (externally) lo root@nn-lp2097769-desktop-dns:~# networkctl IDX LINK TYPE OPERATIONAL SETUP 1 lo loopback carrier unmanaged 307 eth0 ether routable configured root@nn-lp2097769-desktop-dns:~# resolvectl Global Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported resolv.conf mode: stub Link 307 (eth0) Current Scopes: DNS Protocols: +DefaultRoute -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported Current DNS Server: 10.238.94.1 DNS Servers: 10.238.94.1 fd42:7213:f20e:bd74::1 fe80::216:3eff:fe0f:ee29 DNS Domain: lxd # but networkd config for eth0 already gone: root@nn-lp2097769-desktop-dns:~# ls /run/systemd/network/ => empty # now restarting systemd-networkd.service leads to eth0 becoming unmanaged (as the .network file is gone) # and DNS config is dropped root@nn-lp2097769-desktop-dns:~# systemctl restart systemd-networkd root@nn-lp2097769-desktop-dns:~# networkctl IDX LINK TYPE OPERATIONAL SETUP 1 lo loopback carrier unmanaged 307 eth0 ether routable unmanaged root@nn-lp2097769-desktop-dns:~# resolvectl Global Protocols: -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported resolv.conf mode: stub Link 307 (eth0) Current Scopes: none Protocols: -DefaultRoute -LLMNR -mDNS -DNSOverTLS DNSSEC=no/unsupported So the reporducer comes down to: $ apt install ubuntu-settings network-manager && systemctl restart systemd-networkd.service => ubuntu-settings installs /usr/lib/netplan/00-network-manager-all.yaml ("renderer: NetworkManager") => network-manager installation leads to "netplan generate" being executed by the NM-Netplan integration => SOMETHING?? (during "apt install ubuntu-destkop-minimal") restarts systemd-networkd.service, as can be seen from the logs of comment #18: ``` Feb 14 10:17:39 test24 systemd-networkd[839]: enp1s0: Configuring with /run/systemd/network/10-netplan-enp1s0.network. Feb 14 10:17:39 test24 systemd[1]: Started systemd-networkd.service - Network Configuration. Feb 14 10:17:39 test24 systemd-networkd[839]: enp1s0: DHCPv4 address 192.168.122.50/24, gateway 192.168.122.1 acquired from 192.168.122.1 Feb 14 10:20:57 test24 systemd[1]: Stopping systemd-networkd.service - Network Configuration... Feb 14 10:20:57 test24 systemd-networkd[839]: enp1s0: DHCPv6 lease lost Feb 14 10:20:57 test24 systemd[1]: systemd-networkd.service: Deactivated successfully. Feb 14 10:20:57 test24 systemd[1]: Stopped systemd-networkd.service - Network Configuration. Feb 14 10:20:57 test24 systemd[1]: Starting systemd-networkd.service - Network Configuration... Feb 14 10:20:57 test24 systemd-networkd[14398]: lo: Link UP Feb 14 10:20:57 test24 systemd-networkd[14398]: lo: Gained carrier Feb 14 10:20:57 test24 systemd-networkd[14398]: enp1s0: Link UP Feb 14 10:20:57 test24 systemd-networkd[14398]: enp1s0: Gained carrier Feb 14 10:20:57 test24 systemd-networkd[14398]: enp1s0: Gained IPv6LL Feb 14 10:20:57 test24 systemd-networkd[14398]: Enumeration completed ``` With those 3 circumstances coming together, we end up in a situation where "netplan generate" already produced configuration for the new setup, but "netplan apply" was not yet executed, enabling that new configuration. But systemd-networkd.service gets restarted picking up the new configuration already (outside of Netplan's control), therefore both networking daemons now don't feel responsible to manage the interface/DNS. IMO this could be fixed in 3 different ways: 1/ not having "renderer: NetworkManager" in the netplan configuration # but we actually want to have NM managing the network after a reboot. 2/ not calling "netplan generate" from NetworkManager (LP: #2090848) 3/ not restarting systemd-networkd.service during "apt install ubuntu-desktop-minimal" Whereas the simple workaround would be to execute: $ netplan apply => This will put control for the interface in NetworkManager's hands, as described in the Netplan configuration. DNS will be working again. @enr0n, do you have any idea why systemd-networkd.service would be restarted during "apt install ubuntu-desktop-minimal"? ** Changed in: systemd (Ubuntu) Status: Incomplete => Confirmed ** Changed in: netplan.io (Ubuntu) Status: New => Triaged ** Changed in: netplan.io (Ubuntu) Importance: Undecided => Medium ** Tags added: server-triage-discuss -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/2097769 Title: Installation of ubuntu-desktop-minimal breaks DNS Status in netplan.io package in Ubuntu: Triaged Status in systemd package in Ubuntu: Confirmed Bug description: After performing an autoinstall with Ubuntu Server ISO and rebooting, trying to automate the installation of ubuntu-desktop-minimal causes DNS settings to be lost. For our specific use-case, we are installing ubuntu server (fully automated), then using Puppet to install desktop packages. This was working without any manual interaction previously on both Ubuntu 22.04 and 24.04 For the last week or so, deployments of 24.04 (22.04 is still fine) are getting stuck after installing ubuntu-desktop-minimal. The DNS server settings are lost, but IP connectivity remains. Step-by-step 1) Install Ubuntu Server with default network configuration using autoinstall. 2) Reboot and install network-manager (note that everything is still working normally) 3) Install ubuntu-desktop-minimal DNS settings are now lost on the primary interface, yet IP connectivity remains. networkd is still managing the interface, but "netplan get" reports that NetworkManager is the current renderer. ``` network: version: 2 renderer: NetworkManager ethernets: enp1s0: critical: true nameservers: addresses: - 172.16.1.100 - 172.18.1.100 dhcp-identifier: "mac" dhcp4: true ``` We can workaround the problem forcing an extra reboot after installing ubuntu-desktop-minimal. But previously this workflow was fine without rebooting until the very end of the config. ProblemType: Bug DistroRelease: Ubuntu 24.04 Package: systemd 255.4-1ubuntu8.5 ProcVersionSignature: Ubuntu 6.8.0-52.53-generic 6.8.12 Uname: Linux 6.8.0-52-generic x86_64 ApportVersion: 2.28.1-0ubuntu3.3 Architecture: amd64 CasperMD5CheckResult: pass CloudArchitecture: x86_64 CloudID: none CloudName: none CloudPlatform: none CloudSubPlatform: config Date: Mon Feb 10 10:47:43 2025 InstallationDate: Installed on 2025-02-10 (0 days ago) InstallationMedia: Ubuntu-Server 24.04.1 LTS "Noble Numbat" - Release amd64 (20240827) Lsusb: Error: command ['lsusb'] failed with exit code 1: Lsusb-t: Lsusb-v: Error: command ['lsusb', '-v'] failed with exit code 1: MachineType: VMware, Inc. VMware7,1 ProcEnviron: LANG=en_GB.UTF-8 PATH=(custom, no user) SHELL=/bin/bash TERM=xterm-256color ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.8.0-52-generic root=/dev/mapper/vg00-root ro RebootRequiredPkgs: Error: path contained symlinks. SourcePackage: systemd SystemdFailedUnits: Error: command ['systemctl', 'status', '--full', '●'] failed with exit code 4: Invalid unit name "●" escaped as "\xe2\x97\x8f" (maybe you should use systemd-escape?). Unit \xe2\x97\x8f.service could not be found. ------ Error: command ['systemctl', 'status', '--full', '●'] failed with exit code 4: Invalid unit name "●" escaped as "\xe2\x97\x8f" (maybe you should use systemd-escape?). Unit \xe2\x97\x8f.service could not be found. UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 06/25/2021 dmi.bios.vendor: VMware, Inc. dmi.bios.version: VMW71.00V.18227214.B64.2106252220 dmi.board.name: 440BX Desktop Reference Platform dmi.board.vendor: Intel Corporation dmi.board.version: None dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 1 dmi.chassis.vendor: No Enclosure dmi.chassis.version: N/A dmi.modalias: dmi:bvnVMware,Inc.:bvrVMW71.00V.18227214.B64.2106252220:bd06/25/2021:svnVMware,Inc.:pnVMware7,1:pvrNone:rvnIntelCorporation:rn440BXDesktopReferencePlatform:rvrNone:cvnNoEnclosure:ct1:cvrN/A:sku: dmi.product.name: VMware7,1 dmi.product.version: None dmi.sys.vendor: VMware, Inc. 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