AP mode for Wifi on Ubuntu

iw list to check if it is supported.

$ iw list
...
...
Supported interface modes:
               * IBSS
               * managed
               * AP
               * P2P-client
               * P2P-GO
...
...

use nmcli to enable

$ sudo nmcli d wifi hotspot ifname "wifi-if-name" ssid "ssid-name" password "ssid-passwd"

ex:
$ sudo nmcli d wifi hotspot ifname wlan0 ssid TestHop password 12345678
[sudo] password for nvidia:

Device 'wlan0' successfully activated with '....................'.
Hint: "nmcli dev wifi show-password" shows the Wi-Fi name and password.
nvidia@tegra-ubuntu:~
$ nmcli connection show
NAME                UUID                                  TYPE      DEVICE
Hotspot             ....................................  wifi      wlan0
l4tbr0              ....................................  bridge    l4tbr0
Wired connection 1  ....................................  ethernet  --