[Bug 2141584] Re: Sending wakeonlan magic packet from kernel 6.8.0-100-generic no longer works (UDP broadcast wrong destination address)

Was pointed towards this bug after mistakingly responding to a different bug. I also had this problem and reverted back to -94 and wakeonlan functionality instantly returned.
I noticed it right after updating because my backup device wasn't waking up anymore (done through a cronjob) causing the cronjob that follows 5 minutes after to fail.

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Title:
Sending wakeonlan magic packet from kernel 6.8.0-100-generic no longer
works (UDP broadcast wrong destination address)

Status in linux package in Ubuntu:
Fix Released
Status in linux source package in Jammy:
Fix Released
Status in linux source package in Noble:
Fix Committed
Status in linux source package in Questing:
Fix Released

Bug description:
I'm using the "wakeonlan" tool to wake up some PCs by sending a magic packet from Ubuntu 24.04.
After upgrading to kernel 6.8.0-100-generic, I'm unable to wake up all PCs, because the destination UDP address is no longer FF:FF:FF:FF:FF:FF

---
This is a tcpdump of a working magic packet, generated with the previous kernel

Kernel 6.8.0-90-generic

root@apps1:~# wakeonlan 20:88:10:74:9f:4d

In another terminal window:

root@apps1:~# tcpdump -n -i ens192 port 9 -e
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on ens192, link-type EN10MB (Ethernet), snapshot length 262144 bytes
18:54:22.016746 00:50:56:a7:d3:1b > ff:ff:ff:ff:ff:ff, ethertype IPv4 (0x0800), length 144: 192.168.98.22.56625 > 255.255.255.255.9: UDP, length 102

everything is fine, and the destination PC wakes up.

With the latest 6.8.0-100-generic kernel, the magic packet is no
longer sent to the ethernet broadcast address. It is sent to a
specific mac address, in my case this is the default gateway mac
address! See below.

Kernel 6.8.0-100-generic

root@apps1:~# wakeonlan 20:88:10:74:9f:4d

In another terminal window:

root@apps1:~# tcpdump -n -i ens192 port 9 -e
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on ens192, link-type EN10MB (Ethernet), snapshot length 262144 bytes
19:00:19.581282 00:50:56:a7:d3:1b > 00:e2:69:59:27:42, ethertype IPv4 (0x0800), length 144: 192.168.98.22.55456 > 255.255.255.255.9: UDP, length 102

As you can see, the destination MAC address is no longer
ff:ff:ff:ff:ff:ff. It's now my default gateway MAC address.

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.8.0-100-generic 6.8.0-100.100
ProcVersionSignature: Ubuntu 6.8.0-100.100-generic 6.8.12
Uname: Linux 6.8.0-100-generic x86_64
AlsaDevices:
total 0
crw-rw---- 1 root audio 116, 1 feb 11 19:00 seq
crw-rw---- 1 root audio 116, 33 feb 11 19:00 timer
AplayDevices: Error: [Errno 2] No such file or directory: 'aplay'
ApportVersion: 2.28.1-0ubuntu3.8
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord'
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CRDA: N/A
CasperMD5CheckResult: unknown
Date: Wed Feb 11 19:32:07 2026
IwConfig: Error: [Errno 2] No such file or directory: 'iwconfig'
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. VMware Virtual Platform
PciMultimedia:

ProcFB: 0 vmwgfxdrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.8.0-100-generic root=UUID=5f9c0200-f23e-11e8-8f30-000c29534382 ro maybe-ubiquity
RelatedPackageVersions:
linux-restricted-modules-6.8.0-100-generic N/A
linux-backports-modules-6.8.0-100-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.23
RfKill: Error: [Errno 2] No such file or directory: 'rfkill'
SourcePackage: linux
UpgradeStatus: Upgraded to noble on 2024-09-02 (527 days ago)
dmi.bios.date: 11/12/2020
dmi.bios.release: 4.6
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: 6.00
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.ec.firmware.release: 0.0
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvr6.00:bd11/12/2020:br4.6:efr0.0:svnVMware,Inc.:pnVMwareVirtualPlatform:pvrNone:rvnIntelCorporation:rn440BXDesktopReferencePlatform:rvrNone:cvnNoEnclosure:ct1:cvrN/A:sku:
dmi.product.name: VMware Virtual Platform
dmi.product.version: None
dmi.sys.vendor: VMware, Inc.

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