Public bug reported:

Ubuntu 24.04.4 LTS
Kernel: 7.0.0-30-generic
HWE package: linux-generic-hwe-24.04 7.0.0-30.30~24.04.1

Hardware:
Lenovo ThinkPad T480
Intel AX210 Wi-Fi 6E
iwlwifi
Xfinity XB7 / Technicolor CGM4331COM gateway

Problem:

When connected to the XB7 5 GHz network, the AX210 falls back to
legacy 54 Mbit/s rates.

iw reports approximately:

rx bitrate: 54.0 MBit/s
tx bitrate: 54.0 MBit/s

Internet throughput is approximately 16 Mbit/s despite excellent
signal (~-40 dBm).

dmesg repeatedly reports:

wlp3s0: required MCSes not supported, disabling HT

The XB7 advertises HT, VHT, HE and 80 MHz operation.

Control tests:

1. Same T480/AX210/kernel connected to an iPhone 5 GHz hotspot:
   rx bitrate: 1200.9 MBit/s
   80MHz HE-MCS 11 HE-NSS 2

2. iPhone connected directly to the same XB7:
   Internet download approximately 679 Mbit/s.

AX210 hardware and internet connection both appear
healthy. The issue appears specific to mac80211's HT/MCS negotiation
with the XB7.

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-7.0.0-30-generic 7.0.0-30.30~24.04.1
ProcVersionSignature: Ubuntu 7.0.0-30.30~24.04.1-generic 7.0.12
Uname: Linux 7.0.0-30-generic x86_64
ApportVersion: 2.28.3-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
 USER        PID ACCESS COMMAND
 /dev/snd/controlC0:  logan      3333 F.... wireplumber
 /dev/snd/seq:        logan      3328 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Fri Aug 28 23:28:56 2026
InstallationDate: Installed on 2024-11-16 (651 days ago)
InstallationMedia: Ubuntu 24.04.1 LTS "Noble Numbat" - Release amd64 
(20240827.1)
MachineType: LENOVO 20L6S45K00
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-30-generic 
root=UUID=c78796f1-2f9d-46e7-81e2-10a3fdc4b28e ro quiet splash 
intel_pstate=Active i915.enable_dpcd_backlight=0 vt.handoff=7
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No 
PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
 linux-restricted-modules-7.0.0-30-generic N/A
 linux-backports-modules-7.0.0-30-generic  N/A
 linux-firmware                            20240318.git3b128b60-0ubuntu2.29
SourcePackage: linux-hwe-7.0
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 09/06/2025
dmi.bios.release: 1.56
dmi.bios.vendor: LENOVO
dmi.bios.version: N24ET81W (1.56 )
dmi.board.asset.tag: Not Available
dmi.board.name: 20L6S45K00
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697 WIN
dmi.chassis.asset.tag: No Asset Information
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: None
dmi.ec.firmware.release: 1.22
dmi.modalias: 
dmi:bvnLENOVO:bvrN24ET81W(1.56):bd09/06/2025:br1.56:efr1.22:svnLENOVO:pn20L6S45K00:pvrThinkPadT480:rvnLENOVO:rn20L6S45K00:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20L6_BU_Think_FM_ThinkPadT480:pfaThinkPadT480:
dmi.product.family: ThinkPad T480
dmi.product.name: 20L6S45K00
dmi.product.sku: LENOVO_MT_20L6_BU_Think_FM_ThinkPad T480
dmi.product.version: ThinkPad T480
dmi.sys.vendor: LENOVO
modified.conffile..etc.cron.daily.apport: [deleted]

** Affects: linux-hwe-7.0 (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug noble wayland-session

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https://bugs.launchpad.net/bugs/2165808

Title:
  Intel AX210 falls back to 54 Mbps with Xfinity XB7 — "required MCSes
  not supported, disabling HT"

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