[Bug 2049303] Re: MT7921 - IPv6 no longer working (Not receiving Multicast)

[Rudi Daemen]

Correcting "affecting" value.

** Package changed: ubuntu-release-upgrader (Ubuntu) => linux-signed-
hwe-6.5 (Ubuntu)

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https://bugs.launchpad.net/bugs/2049303

Title:
  MT7921 - IPv6 no longer working (Not receiving Multicast)

Status in linux-signed-hwe-6.5 package in Ubuntu:
  New

Bug description:
  After updating to kernel linux-image-6.5.0-14-generic, IPv6 stopped working with the MT7921 wifi card.
  No errors are logged, but when using tcpdump / wireshark to capture traffic, I can see the MT7921 card no longer appears to receive IPv6 Multicast (thus it never receives the Router Advertisements, etc.).

  Booting back to the previous kernel image (linux-
  image-6.2.0-39-generic) resolves the issue and IPv6 Multicast works
  fine and IPv6 connectivity works fine again.

  The system is configured to use the 22.04 HWE kernel to better support
  the AMD Advantage Platform hardware (ASUS ROG Strix G513QY).

  Steps to reproduce:
  1. Have Ubuntu 22.04 LTS installed on a laptop with MT7921 Wifi adapter and connect it to a Dual-stack network leveraging Router Advertisements for IPv6.

  2. Run it with HWE Kernel image linux-image-6.2.0-39-generic and observe the following:
  - IPv6 stateless autoconfiguration works and a public/global address is assigned.
  - Inbound IPv6 Multicast packets are seen when using tcpdump/wireshark.

  3. Update the HWE Kernel to linux-image-6.5.0-14-generic and observe the following:
  - IPv6 only configures link-local address (fe80::) and no public/global address.
  - No inbound IPv6 multicast packets are seen when using tcpdump/wireshark.

  
  fludizz at pauwel:~$ lsb_release -rd
  Description:	Ubuntu 22.04.3 LTS
  Release:	22.04

  Network card in question:
  05:00.0 Network controller: MEDIATEK Corp. MT7921 802.11ax PCI Express Wireless Network Adapter
  	Subsystem: AzureWave Device 4680
  	Flags: bus master, fast devsel, latency 0, IRQ 83, IOMMU group 14
  	Memory at fc30300000 (64-bit, prefetchable) [size=1M]
  	Memory at fc30400000 (64-bit, prefetchable) [size=16K]
  	Memory at fc30404000 (64-bit, prefetchable) [size=4K]
  	Capabilities: [80] Express Endpoint, MSI 00
  	Capabilities: [e0] MSI: Enable+ Count=1/32 Maskable+ 64bit+
  	Capabilities: [f8] Power Management version 3
  	Capabilities: [100] Vendor Specific Information: ID=1556 Rev=1 Len=008 <?>
  	Capabilities: [108] Latency Tolerance Reporting
  	Capabilities: [110] L1 PM Substates
  	Capabilities: [200] Advanced Error Reporting
  	Kernel driver in use: mt7921e
  	Kernel modules: mt7921e

  
  fludizz at pauwel:~$ apt-cache policy linux-image-6.5.0-14-generic
  linux-image-6.5.0-14-generic:
    Installed: 6.5.0-14.14~22.04.1
    Candidate: 6.5.0-14.14~22.04.1
    Version table:
   *** 6.5.0-14.14~22.04.1 500
          500 http://nl.archive.ubuntu.com/ubuntu jammy-updates/main amd64 Packages
          500 http://security.ubuntu.com/ubuntu jammy-security/main amd64 Packages
          100 /var/lib/dpkg/status

  Note: The WiFi device is using the same firmware version on both
  kernels.

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