For making remote ssh connection on raspberry pi 3B (os raspbian), it need to close wifi connection (to use only wired connection instead), I have found the command on SE is
sudo iwconfig wlan0 txpower off
But the problem is now I cant switch on back the wifi. I have used the code
sudo iwconfig wlan0 txpower on
it shows error,
Error for wireless request "Set Tx Power" (8B27) : GET failed on device wlan0 ; Input/output error.
Now what is the way to get the wifi again?