NetworkManager acd conflict after Tumbleweed update

English Network/Internet
1

This morning after updating Tumbleweed last night my wired connection stopped working. At the moment after many systemctl starts and restarts Firefox has internet although it refuses to connect to the Huawei AX3 router management page and not showing up on my cell’s management app, is what I’m using at the moment on Firefox. Firefox is connected through the AX3 to fibre internet. I can’t ping from the command line.
This is what systemctl says:

ping 8.8.8.8

ping: connect: Network is unreachable
ArbuthnotT:/data/packages # systemctl status NetworkManager
● NetworkManager.service - Network Manager
Loaded: loaded (/usr/lib/systemd/system/NetworkManager.service; enabled; preset: disabled)
Active: active (running) since Wed 2026-04-22 13:48:37 SAST; 20min ago
Invocation: 0e2a588ffcb948ef806ba94a1cde4fc8
Docs: man:NetworkManager(8)
Main PID: 9833 (NetworkManager)
Tasks: 5 (limit: 9372)
CPU: 714ms
CGroup: /system.slice/NetworkManager.service
└─9833 /usr/sbin/NetworkManager --no-daemon

Apr 22 13:52:50 ArbuthnotT NetworkManager[9833]: [1776858770.0261] device (enp2s0): IP address 192.168.3.18 cannot be configured because it is already in use in the network by host E6:FA:C4:06:47:04
Apr 22 13:53:09 ArbuthnotT NetworkManager[9833]: [1776858789.8572] device (enp2s0): IP address 192.168.3.18 cannot be configured because it is already in use in the network by host E6:FA:C4:06:47:04
Apr 22 13:54:09 ArbuthnotT NetworkManager[9833]: [1776858849.7391] dhcp4 (enp2s0): state changed new lease, address=192.168.3.18, acd conflict
Apr 22 13:54:29 ArbuthnotT NetworkManager[9833]: [1776858869.7689] dhcp4 (enp2s0): state changed new lease, address=192.168.3.18, acd conflict
Apr 22 13:55:09 ArbuthnotT NetworkManager[9833]: [1776858909.7984] dhcp4 (enp2s0): state changed new lease, address=192.168.3.18, acd conflict
Apr 22 13:56:29 ArbuthnotT NetworkManager[9833]: [1776858989.8280] dhcp4 (enp2s0): state changed new lease, address=192.168.3.18, acd conflict
Apr 22 13:59:09 ArbuthnotT NetworkManager[9833]: [1776859149.8568] dhcp4 (enp2s0): state changed new lease, address=192.168.3.18, acd conflict
Apr 22 14:01:23 ArbuthnotT NetworkManager[9833]: [1776859283.3673] audit: op=“statistics” interface=“enp2s0” ifindex=2 args=“2000” pid=1797 uid=1000 result=“success”
Apr 22 14:02:51 ArbuthnotT NetworkManager[9833]: [1776859371.0205] audit: op=“connection-update” uuid=“602c326d-7c44-3c7d-bfc6-912602afe5b8” name=“Wired connection 1” args=“ipv4.may-fail,ipv4.dns” pid=8044 uid=1000 result="suc>
Apr 22 14:04:09 ArbuthnotT NetworkManager[9833]: [1776859449.8848] dhcp4 (enp2s0): state changed new lease, address=192.168.3.18, acd conflict

After googling I understand an “acd conflict” is when two different devices get the same dhcp address. Network manager apparently has had the acd detection added recently and causes a hang when starting as mine is doing.
I tried using Yast Network to change to wicked but it won’t complete the operation due to a problem with /etc/sysctl.conf which on examination is pristine.
I have a dual boot system with a Tumbleweed root and opt partition and a Leap:16.0 root and opt partition. Home is shared between both distributions.
When I switched to my Leap system NetworkManager had the same problem but after a restart the problem went away so it could be a shared configuration in home.
There’s a method of turning off NetworkManager’s conflict detection to speed up the boot process but I can only find Arch and Ubuntu fixes which don’t look like they match openSUSE.
Please help

2

To add to this, if I install dhcp-client and run it, I can access the router. From this I understand that NetworkManager’s dhcp client is faulty.

3

@plater Hi, what does the connection show, eg;

nmcli con show
NAME                UUID                                  TYPE      DEVICE 
iSCSI                 ....................................ethernet  ens4f0

nmcli con show "iSCSI" | grep ipv4.dad-timeout
ipv4.dad-timeout:                       -1 (default)
4

nmcli con show

NAME UUID TYPE DEVICE
Wired connection 1 602c326d-7c44-3c7d-bfc6-912602afe5b8 ethernet enp2s0
lo 54715a14-de2f-465f-9f80-e35467a54b76 loopback lo
enp3s0 39da702a-74d8-382f-92b9-186d04f18f8d ethernet –

5

@plater and the other command… nmcli con show "Wired connection" | grep ipv4.dad-timeout

6

nmcli con show “Wired connection 1” | grep ipv4.dad-timeout
ipv4.dad-timeout: -1 (default)
From what I’ve seen changing ipv4.dad-timeout to 0 may fix my problem.

7

@plater Something has changed somewhere else then… maybe reboot your router?

That’s been the default for some time…

Ref: https://networkmanager.dev/docs/api/1.54.3/settings-ipv4.html

Yes a 0 will disable, or maybe 100?

8

I’ve opened a bug https://bugzilla.suse.com/show_bug.cgi?id=1262575 I’ve restarted router and checked my cable before I posted here.

9

And setting the timeout to 0 works around the problem.