802.11ac was supposed to be compatible with Pi 4, right? I recently tried using 802.11ac only to maximize the WiFi performance, but as soon as I did that, the Pi disconnected I have & to enable 802.11n in order for the Pi to connect to that SSID.
When I used nmcli dev wifi connect password I get the error saying "secrets were required but not provided", even with the --ask option.
I have Ubuntu Server 20.04 on my Raspberry Pi 4B 2GB, which I'm using as my AirPlay receiver.
I tried using Netplan based on this solution after reinstalling Ubuntu Server, but WiFi remained disconnected unless I reenable 802.11n.
nmcli
won't help. You should ask on a Ubuntu site. Configuration using yaml should be independent of hardware (other than device names).