Raspberry Pi 3B+ Auto reconnect to wifi when lost connect

RPi3-Auto-WiFi.md

Auto reconnect to wifi when lost connection

Before you start, make sure ip command is available on your system. In modern Linux distributions, ip replaces older ifconfig command. If net-tools package (that includes ifconfig) is not installed and you prefer using it, you can install it via sudo apt-get install net-tools.

Create script file

Use touch /home/pi/wifi-reconnect.sh to create a shell script file, with the following content:

#!/bin/bash

SSID=$(/sbin/iwgetid --raw)

if [ -z "$SSID" ]; then
    echo "`date -Is` WiFi interface is down, trying to reconnect" >> /home/pi/wifi-log.txt
    if command -v /sbin/ip &> /dev/null; then
        /sbin/ip link set wlan0 down
        sleep 10
        /sbin/ip link set wlan0 up
    elif command -v sudo ifconfig &> /dev/null; then
        sudo ifconfig wlan0 down
        sleep 10
        sudo ifconfig wlan0 up
    else
        echo "`date -Is` Failed to reconnect: neither /sbin/ip nor ifconfig commands are available" >> /home/pi/wifi-log.txt
    fi
fi

echo 'WiFi check finished'

Or you can also use the following command to download the script.

sudo wget https://raw.github.com/carry0987/Raspberry-Pi-Repo/master/Auto-WiFi-Reconnect/wifi-reconnect.sh

Note:

This script uses /sbin/ip command for disabling and enabling the wlan interface. This is a more modern approach compared to using ifconfig and is the preferred way in newer Linux distributions.

Make new file executable

sudo chmod +x /home/pi/wifi-reconnect.sh

Install cron

sudo apt-get install cron

Edit crontab

Use sudo vim /etc/crontab to edit crontab

By putting the following content at the end of the file:

* * * * * root /home/pi/wifi-reconnect.sh

Test it by disconnecting from WiFi:

/sbin/ip link set wlan0 down

The script should reestablish the connection within 1 minute.

Check log file

After the RPi reestablishes the connection, reconnect to the RPi and check the log file:
cat /home/pi/wifi-log.txt

I have a Powerwall 2 and rpi5 running Trixie and was getting disconnections to the PW WiFi.

Tried out the script on Trixie, but it it also using network manager and wants
nmcli connection down/up <SSID>
Which works well for me.

I’m not super familiar with Network Manager, so not sure the best way to add that in as a check and option for your script.
Can maybe test by using nmcli connection show | grep $SSID to see if configured.

I also did some one time configs:
Set the auto retries for that SSID, as suggested by @cvaziri1
sudo nmcli connection modify TEG-XXX connection.autoconnect-retries 0

and set the band to only b/g/n
sudo nmcli connection modify TEG-XXX 802-11-wireless.band bg

and disabled power saving
sudo nmcli connection modify TEG-XXX 802-11-wireless.powersave 2

$ sudo nmcli connection show TEG-XXX | grep "save\|band\|autoconnect-retries"
connection.autoconnect-retries:         0 (forever)
802-11-wireless.band:                   bg
802-11-wireless.powersave:              2 (disable)