Comment 12 for bug 1869587

>02:00.0 Network controller: Intel Corporation Wireless 8265 / 8275 (rev 78)
>firmware=36.77d01142.0

backport-iwlwifi-dkms was completly unstable (drop udp packet bigger than somes bytes )
After removing it worked but with slow speed ..

Without backport-iwlwifi-dkms, wifi was slow on Focal until the last kernel update.
With 5.4.0-31 I recover good performance with over 100Mbs.
Before this kernel it was aroud 3-10Mbs/s
If I remember well I think built-in wifi was slow since my upgrade to focal ( probably starting with 5.4.0-25)

For Focal users , remove backport-iwlwifi-dkms and UPDATE your kernel

There is 3 fix for iwlwifi in https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4.31
and more pending to get into Focal maybe
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4.33
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4.36

I have play a lot with driver option to try to recover stability and performance before this kernel update ..
I now use in
/etc/modprobe.d/iwlwifi.conf:
>options iwlwifi debug=1 swcrypto=1 disable_msix=1 disable_11ac=1 disable_11ax=1 power_save=0 bt_coex_active=0

I will check later if I can revert some of this options to default value with 5.4.0-31

Good luck to all