Comment # 28 on bug 1163771 from Freek de Kruijf

(In reply to Clemens Famulla-Conrad from comment #27)
> I'm not sure what cause your problem. I also tried wicked+wlan on a just
> updated tumbleweed and didn't got any problems with WPA_PSK config like:
> 
> > BOOTPROTO='dhcp'
> > STARTMODE='auto'
> > WIRELESS_MODE='Managed'
> > WIRELESS_AUTH_MODE='psk'
> > WIRELESS_ESSID='XYZ'
> > WIRELESS_WPA_PSK='SECRET'

I have the same setup.

> You may also get some wpa_supplicant debugging possibility by enabling the
> control interface and use `wpa_cli` to play around:
> 
> > sed -i '/^ExecStart=/c\ExecStart=/usr/sbin/wpa_supplicant -c /etc/wpa_supplicant/wpa_supplicant.conf -u -t -f /var/log/wpa_supplicant.log -O /var/run/wpa_supplicant' /usr/lib/systemd/system/wpa_supplicant.service
> > systemctl daemon-reload
> > systemctl restart wpa_supplicant.service
> > rcwickedd restart
> >  
> > wpa_cli
> >  > log_level debug
> >  > list_networks
> >  > password X Y
> >  > status
> >  > disconnect
> >  > reconnect

Played with it and most of the time the interface did not see my AP when
scanning.
Also used "iwlist wlan0 scan" and had the same result; only occasionally my AP
was listed.
My RPi4 is only 8 m from the AP, so I moved it closer to the AP and that gave
me a connection.

Conclusion the WiFi interface of the the RPi4 is rather weak. Nothing wrong
anymore with the software.