How to set radio to Soft AP mode?

If you don't want simultaneous ap/sta, you can run the commands:

nmcli conn add type wifi ifname wlan0 con-name softAP autoconnect no ssid softAP

nmcli conn modify softAP 802-11-wireless.mode ap 802-11-wireless.band bg 802-11d

nmcli conn up softAP

You can also do it via wpa_supplicant .conf files if you do not have nmcli.