WiFi how to automatically connect back to a preferred SSID when available

Question

Since wifi-radar is not yet available on ubuntu 20.04, I go to explain my need

I have two WiFi networks, the main WiFi has SSID Main

the other is a sort of backup and it has a low signal and poor performance, let's call its SSID Emerg

Sometime the Main SSID becomes unavailable I suppose for some sort of interference, so I manually switch to connect to the Emerg WiFi

When Main returns available ... obviously the WiFi remains connected to the Emerg

Well here it comes the question

Is it possible to setup the WiFi in such a way that when Main SSID returns available, the WiFi goes automatically back to connect to Main ?

Answer 1

Create a new script with :

sudo nano /usr/local/bin/back-wifi-main

Paste the following content (replace by your Wifi password)

#!/bin/bash
Get the current Wifi
current=$(iwconfig 2>/dev/null | grep ESSID | cut -f 2 -d ")
if [ $current == "Emerg" ] ; then
    # Check if Wifi is back
    if nmcli d wifi list | grep '^\ ' | grep "Main" ; then
       # Reconnect to your wifi
        nmcli d wifi connect Main <password>
    fi
fi

Make it executable

sudo chmod +x /usr/local/bin/back-wifi-main

Finally add this script into a crontab

sudo crontab -e

and paste the following content to check every 5 minutes

*/5 * * * * /usr/local/bin/back-wifi-main