Intel Wi-Fi 6 AX200 [8086:2723] Subsystem [1a56:1653] Performance slow/unusable after upgrade from 19.10 -> 20.04

[Don]

Per instruction in https://bugs.launchpad.net/ubuntu/+source/backport-iwlwifi-dkms/+bug/1869587/comments/10, I am filing a separate bug that is probably related to #1869587.

After upgrading my Dell XPS 13 7390 Developer Edition from Kubuntu 19.10 -> 20.04, wifi performance was almost non-existent. After following the guidance here - https://askubuntu.com/questions/1230525/ubuntu-20-04-network-performance-extremely-slow, I uninstalled backport-iwlwifi-dkms, and wifi performance seems to have gone back to "normal".

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: backport-iwlwifi-dkms (not installed)
ProcVersionSignature: Ubuntu 5.4.0-29.33-generic 5.4.30
Uname: Linux 5.4.0-29-generic x86_64
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: KDE
Date: Wed May 6 19:54:41 2020
InstallationDate: Installed on 2019-11-24 (165 days ago)
InstallationMedia: Kubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
SourcePackage: backport-iwlwifi-dkms
UpgradeStatus: Upgraded to focal on 2020-04-29 (8 days ago)

[Don (mogul345)]

In the referenced bug, another reporter was asked to give the output of lspci -nnk. In case it helps, here's the output of the command from my machine:

00:00.0 Host bridge [0600]: Intel Corporation Device [8086:9b51]
        Subsystem: Dell Device [1028:0962]
00:02.0 VGA compatible controller [0300]: Intel Corporation Device [8086:9bca] (rev 04)
        DeviceName: To Be Filled by O.E.M.
        Subsystem: Dell Device [1028:0962]
        Kernel driver in use: i915
        Kernel modules: i915
00:04.0 Signal processing controller [1180]: Intel Corporation Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem [8086:1903]
        Subsystem: Dell Xeon E3-1200 v5/E3-1500 v5/6th Gen Core Processor Thermal Subsystem [1028:0962]
        Kernel driver in use: proc_thermal
        Kernel modules: processor_thermal_device
00:08.0 System peripheral [0880]: Intel Corporation Xeon E3-1200 v5/v6 / E3-1500 v5 / 6th/7th/8th Gen Core Processor Gaussian Mixture Model [8086:1911]
        Subsystem: Dell Xeon E3-1200 v5/v6 / E3-1500 v5 / 6th/7th/8th Gen Core Processor Gaussian Mixture Model [1028:0962]
00:12.0 Signal processing controller [1180]: Intel Corporation Comet Lake Thermal Subsytem [8086:02f9]
        Subsystem: Dell Comet Lake Thermal Subsytem [1028:0962]
00:14.0 USB controller [0c03]: Intel Corporation Device [8086:02ed]
        Subsystem: Dell Device [1028:0962]
        Kernel driver in use: xhci_hcd
00:14.2 RAM memory [0500]: Intel Corporation Device [8086:02ef]
        Subsystem: Dell Device [1028:0962]
00:15.0 Serial bus controller [0c80]: Intel Corporation Serial IO I2C Host Controller [8086:02e8]
        Subsystem: Dell Serial IO I2C Host Controller [1028:0962]
        Kernel driver in use: intel-lpss
        Kernel modules: intel_lpss_pci
00:15.1 Serial bus controller [0c80]: Intel Corporation Comet Lake Serial IO I2C Host Controller [8086:02e9]
        Subsystem: Dell Device [1028:0962]
        Kernel driver in use: intel-lpss
        Kernel modules: intel_lpss_pci
00:16.0 Communication controller [0780]: Intel Corporation Comet Lake Management Engine Interface [8086:02e0]
        Subsystem: Dell Comet Lake Management Engine Interface [1028:0962]
        Kernel driver in use: mei_me
        Kernel modules: mei_me
00:1c.0 PCI bridge [0604]: Intel Corporation Device [8086:02bc] (rev f0)
        Kernel driver in use: pcieport
00:1c.6 PCI bridge [0604]: Intel Corporation Device [8086:02be] (rev f0)
        Kernel driver in use: pcieport
00:1d.0 PCI bridge [0604]: Intel Corporation Device [8086:02b0] (rev f0)
        Kernel driver in use: pcieport
00:1d.4 PCI bridge [0604]: Intel Corporation Device [8086:02b4] (rev f0)
        Kernel driver in use: pcieport
00:1f.0 ISA bridge [0601]: Intel Corporation Device [8086:0284]
        Subsystem: Dell Device [1028:0962]
00:1f.3 Audio device [0403]: Intel Corporation Device [8086:02c8]
        Subsystem: Dell Device [1028:0962]
        Kernel driver in use: snd_hda_intel
        Kernel modules: snd_hda_intel, snd_sof_pci
00:1f.4 SMBus [0c05]: Intel Corporation Device [8086:02a3]
        Subsystem: Dell Device [1028:0962]
        Kernel driver in use: i801_smbus
        Kernel modules: i2c_i80...

[You-Sheng Yang (vicamo)]

Hi, could you also attach dmesg log? `journalctl -b -o short > syslog.log` and attach that syslog.log file. And, have you tried removing backport-iwlwifi-dkms?

[Don (mogul345)]

To the second question - yes, per the askubuntu link, I executed `sudo apt remove backport-iwlwifi-dkms`. After I did that, wifi seemed to work normally.

I should note that the output of `lspci -nnk` is from after executing the remove command.

Would it help to re-install the backported driver, and execute both the lspci command and the journalctl command you've asked for? Or is it sufficient to get the output after removal of the backported driver?

[You-Sheng Yang (vicamo)]

Don, I think that's sufficient to know it's the regression caused by outdated backport-iwlwifi-dkms. I'm marking this a duplicate of bug 1869587.