I have this issue whereby a laptop of mine, which is running Linux Mint 21.2, was unable to connect to my 2.4GHz wife connection. I have no issue connecting to the 5GHz connection, only 2.4Ghz is having issue. I turned to linux mint forum, and found this post, which explained the issue, and the solution was to change my backend wifi device from wpa-supplicant to iwd. It seems that the current wifi daemon at that time, which was wpasupplicant was having issue connecting to 2.4GHz wifi connection.
Here are the steps:
1. Install iwd
sudo apt update && sudo apt install iwd -y
2. Create a configuration file in /etc/NetworkManager/conf.d/wifi-backend.conf
sudo nano /etc/NetworkManager/conf.d/wifi-backend.conf
3. Add in below setting
[device]
wifi.backend=iwd
4. Save and exit nano by pressing ctrl-o and then ctrl-x
5. Stop and disable wpa_supplicant daemon
sudo systemctl disable --now wpa_supplicant
6. Start and enable iwd
sudo systemctl enable --now iwd
7. Restart NetworkManager daemon
sudo systemctl restart NetworkManager
And you are good to go. You should now be able to connect to the 2.4GHz wireless, without any issue.
