I upgraded to Ubuntu 20.04 LTS from Kubuntu 18.04 with a clean install (still dual boot with Windows 10). I can see my network with the correct SSID, but when I try connecting, it never authenticates and keeps asking for the password which I am 100% sure is entered correctly.

I can however, connect to my mobile hotspot wireless.

uname -a

Linux mthiagar-ThinkPad-T440s 5.4.0-26-generic #30-Ubuntu SMP Mon Apr 20 16:58:30 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux

dmesg | grep iwl

[    4.444541] Loading modules backported from iwlwifi
[    4.444542] iwlwifi-stack-public:master:8324:9176b151
[    4.582977] iwlwifi 0000:03:00.0: Direct firmware load for iwl-dbg-cfg.ini failed with error -2
[    4.586206] iwlwifi 0000:03:00.0: loaded firmware version 17.bfb58538.0 7260-17.ucode op_mode iwlmvm
[    4.586243] iwlwifi 0000:03:00.0: Direct firmware load for iwl-debug-yoyo.bin failed with error -2
[    4.654758] iwlwifi 0000:03:00.0: Detected Intel(R) Dual Band Wireless AC 7260, REV=0x144
[    4.678917] iwlwifi 0000:03:00.0: base HW address: e8:2a:ea:73:8c:32
[    4.895628] ieee80211 phy0: Selected rate control algorithm 'iwl-mvm-rs'
[    5.308224] iwlwifi 0000:03:00.0 wlp3s0: renamed from wlan0

lspci -knn | grep Net -A3; rfkill list

03:00.0 Network controller [0280]: Intel Corporation Wireless 7260 [8086:08b2] (rev 83)
    Subsystem: Intel Corporation Dual Band Wireless-AC 7260 [8086:c270]
    Kernel driver in use: iwlwifi
    Kernel modules: iwlwifi
0: tpacpi_bluetooth_sw: Bluetooth
    Soft blocked: no
    Hard blocked: no
1: hci0: Bluetooth
    Soft blocked: no
    Hard blocked: no
2: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: no

I'm not an advanced user by any means, so I've only tried the following from reading other threads:

  1. forgetting the network and reconnecting, unchecking connect automatically, and entering the password into the security tab under configuration

  2. reinstalling iwlwifi using sudo apt install backport-iwlwifi-dkms

  3. running sudo service network-manager restart

Any ideas on what may be wrong, and what else I should try? Let me know if more info is needed.

  • Have you checked password encryption method? – ubuntu user Apr 26 '20 at 12:12
  • Yes, it's WPA & WPA2 Personal. This is the right one. – mthiagar Apr 26 '20 at 14:19
  • 1
    Seeing this exact issue on Dell XPS 9560 after upgrading from 18.04 to 20.04. I am able to connect to 5 GHz network, but not able to connect to 2.4 GHz. Were you able to fix this? – serejja May 1 '20 at 16:39
  • See the solution by @chronodekar below. That worked for me. Just note, I had to restart my computer, just restarting network services didn't work. – mthiagar May 1 '20 at 18:40

Can you try editing the file,

$ sudo vi /etc/modprobe.d/iwlwifi.conf

to add the following if you are attempting to connect to a 5g based N network?

options iwlwifi 11n_disable=8

The above line is supposed to enable antenna aggregation.

Or add the following if you want to connec to a 2.4g based G network;

options iwlwifi 11n_disable=1

The above line disables 802.11n mode.

I can confirm that the above works for me on a regular Ubuntu 20.04 (not Kubuntu) with a Lenovo T460s. Spent enough time digging into the issue to make this post on the Ubuntu forums = https://ubuntuforums.org/showthread.php?t=2442177 (the link has more details which might be useful to read about on this issue, but is not relevant as a direct answer to this question).

  • 1
    This solved it! You are awesome, thank you! I'm connecting to a 2.4g based G network so I added options iwlwifi 11n_disable=1 and had to restart. Just running systemctl restart network-manager.service or `sudo service network-manager restart' didn't work. Must restart. – mthiagar May 1 '20 at 18:34
  • Update: So this works, gets me connected, but disabling 802.11n definitely slows things down very noticeably. In any case, it's better than nothing. – mthiagar May 1 '20 at 22:40

You said "disabling 802.11n definitely slows things down". Try to remove backport-iwlwifi-dkms for having no problems with wifi speed

sudo apt install backport-iwlwifi-dkms
  • remove or install? – user2988257 Oct 2 '20 at 18:40
  • remove helped for me – yacheat Oct 5 '20 at 4:51

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