Wireless Interface TXPower Error

I turned-off my built-in wireless network interface using the command:

1iwconfig wlan0 txpower off

Howerver, I can no longer turn-it back on. Logic says just change "off" to "on" but instead, I get this error.

1root@raspberrypi:/home/pi# iwconfig wlan0 txpower on
2Error for wireless request "Set Tx Power" (8B27) :
3    GET failed on device wlan0 ; Input/output error.

Current status of the wireless interface looks like:

1root@raspberrypi:/home/pi# iwconfig wlan0
2wlan0     IEEE 802.11  ESSID:off/any  
3          Mode:Managed  Access Point: Not-Associated   
4          Retry short limit:7   RTS thr:off   Fragment thr:off
5          Encryption key:off
6          Power Management:on

This dated thread for rpi3 (mine is rpi4) https://www.raspberrypi.org/forums/viewtopic.php?f=28&t=160057 doesn't work from my end.

Then I decided to reboot the rpi4 itself. Issue solved.

Another solution - running the below command (note it uses "auto" instead of the assumed "on")

1iwconfig wlan0 txpower auto

First attempt had the same error as using "on" but after runing it the second time, no more errors shown. Checking on 'ifconfig' now shows the wlan0 interface.

Some useful tidbits in https://raspberrypi.stackexchange.com/questions/43720/disable-wifi-wlan0-on-pi-3