Public bug reported:
== Summary ==
The Ubuntu 26.04 installer (subiquity) generates an incomplete Netplan
configuration for wired Ethernet interfaces. It correctly identifies the
NIC using a MAC address match, but omits the `dhcp4: true` directive. As
a result, the interface comes up but never requests a DHCP lease,
receives no IP address or default gateway, and falls back to a
169.254.x.x (APIPA) self-assigned address. All wired network access
fails.
== Steps to reproduce ==
1. Install Ubuntu 26.04 using the subiquity installer on a machine with a wired
Ethernet NIC.
2. Boot the installed system with a wired connection to a DHCP-enabled network.
3. Run: ip addr show
4. Observe that the wired interface has a 169.254.x.x address and no gateway.
5. Run: ping 8.8.8.8
6. Observe: "Network is unreachable"
== Generated (broken) config ==
File: /etc/netplan/00-installer-config.yaml
network:
ethernets:
enp88s0:
match:
macaddress: 90:2e:16:a8:cc:11
set-name: enp88s0
# dhcp4: true is missing
version: 2
wifis: {}
== Expected behaviour ==
The installer should generate a config with dhcp4: true, as it did in
Ubuntu 24.04:
network:
ethernets:
enp88s0:
dhcp4: true
version: 2
wifis: {}
== Workaround ==
Manually add `dhcp4: true` to the ethernet entry in
/etc/netplan/00-installer-config.yaml, then run:
sudo netplan apply
== Impact ==
All wired network connectivity is broken on the installed system. This
affects any machine where the installer uses the match/set-name stanza
for the wired interface, which appears to be the default behaviour in
26.04.
== Environment ==
- Ubuntu 26.04 (fresh install via subiquity)
- NIC: Realtek / enp88s0 (MAC 90:2e:16:a8:cc:11)
- Wired connection to a standard home/office router with DHCP
- WiFi unaffected
** Affects: subiquity (Ubuntu)
Importance: Undecided
Status: New
** Tags: dhcp ethernet netplan network regression wired
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https://bugs.launchpad.net/bugs/2156838
Title:
Subiquity installer omits dhcp4:true for wired ethernet in generated
Netplan config, causing no IP assignment on wired connections
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