Wifi connection lost, do I have some logs?

Hi! I have an arduino yun connected to my wifi with upgraded image and sd boot. Everything working properly but sometimes the connection is lost and the yun resets the wifi configuration and opens the access point.

I don't know exactly why it happens: I think that during the night time the network goes in my home router and the arduino do not find the correct wifi and reset itself.

It seems to me (but my linux knowledge are very limited) that logging is disabled due to flash limitation memory (/var/log contains empty files).. isn't it? I just found log read, but nothing helps..

Is there any log I can check? How can I understand where the problem is? How can disable the wifi configuration reset? Is it sane? Can the sd-boot be the cause of the problem? How can I enable the logs again to understand when and why the wifi connection is resetted? Any kind of helps?

I have an OpenWRT router so I can also write something in the router to see if something goes wrong.. but.. what? (sorry I'm a beginner in the openwrt-network linux side)

It is a very strange situation.. The yun works properly with both processors for days but sometimes the dark side of the stars throw this black spell over my yun and nothing works, I have to connect to the ArduinoYun, set again the wireless password, and reboot it. Kind of annoying.

Make your Yun wifi bulletproof;-

  1. To confirm wifi Signal level:

http://forum.arduino.cc/index.php?topic=188101.msg1583665#msg1583665

My Signal: 100%

  1. Check wifi channel spectrum:

The less neighbors is ,the better is. Use channel 9 for best result.

further wifi issues reading

http://forum.arduino.cc/index.php?topic=242136.msg1735765#msg1735765

mantissa00: ... It is a very strange situation.. The yun works properly with both processors for days but sometimes the dark side of the stars throw this black spell over my yun and nothing works, I have to connect to the ArduinoYun, set again the wireless password, and reboot it. Kind of annoying.

Only work arround:

nano /etc/rc.local
# Put your custom commands here that should be executed once
# the system init finished. By default this file does nothing.

#wifi-live-or-reset
boot-complete-notify


exit 0

ok thank you, very helpful.

So, I'd like to replace wifi-live-or-reset with wifi-live-or-log-and-reboot

could it be something like that?:

#!/bin/sh

blink-start 200

IFACE="wlan0"
SLEEP_TIME=2
MAX_SLEEP=60

slept=0

iface_exists=""
iface_is_managed=""
iface_has_ssid=""
iface_is_access_point=""

update_vars() {
    iface_exists=`/usr/sbin/iwconfig $IFACE`
    iface_has_no_ssid=`/usr/sbin/iwconfig $IFACE | grep ESSID\:off\/any`
    iface_is_access_point=`/usr/sbin/iwconfig $IFACE | grep Mode\:Master`
}

wait_for_iface() {
    if [ $slept -gt $MAX_SLEEP ]
    then
        /bin/dmesg > /last_dmesg_with_wifi_errors.log
        /bin/sync
#        /sbin/uci set "arduino.@arduino[0].wifi_reset_step=timed_out"
#        /sbin/uci commit arduino
#        /usr/bin/wifi-reset-and-reboot
        exit 1
    fi

    sleep $SLEEP_TIME
    slept=$(($slept + $SLEEP_TIME))

    update_vars
}

update_vars

while [ true ]
do
    if [ "$iface_exists" = "" ]
    then
        wait_for_iface
#    elif [ "$iface_is_access_point" != "" ]
#    then
#        blink-stop
#        exit 0
#    elif [ "$iface_has_no_ssid" != "" ]
#    then
#        wait_for_iface
    else
        blink-stop

        # log down and reboot!
        now=$(date)
        cp /last_dmesg_with_wifi_errors.log "/www/log/last_dmesg_with_wifi_errors_$now.log"
        echo "$now : wifi down, rebooting."

        rm -f /last_dmesg_with_wifi_errors.log
        exit 0
    fi
done

is it correct?

Should not be hurt. Why not give it try.

it seems to work.. I will see.. : )

ok there is something very strange happening…

The yun is up, I can ping it and ssh into it, because I remember its ip
BUT

In the configuration page of my router (an old to-link with openwrt on it) I can not see the ip address:

(I know that is that machine because I know the mac address and I can ping and ssh because I know the ip it had yesterday via dhcp)

So… what can it be?

-74 dBm, signal is poor.

http://forum.arduino.cc/index.php?topic=188101.msg1597553#msg1597553

Your Link Quality= 35%, mine is 100%.

Also with the new workaround script (do not reset configuration) after some days the yun lost the connection and the white led in the board is off.

I have tried to move the router and now if I go in the router control panel the mac address of the yun has Signal Noise RX Rate TX Rate -88 dBm 0 dBm 28.9 Mbit/s, MCS 3, 20MHz 21.7 Mbit/s, MCS 2, 20MHz

if I go in the yun luci (advanced panel) I can see the ip of the router with those values: -71 dBm -88 dBm 13.0 Mbit/s, MCS 1, 20MHz 28.9 Mbit/s, MCS 3, 20MHz

The router is ~7-8 meter. Honestly I don't think it is really a problem of wifi strength. Am I wrong?

It has to say that I'm using yun openwrt sys upgrade 1.2 (I have installed a bunch of things and if it is possible I won't format everything) and bootable sd card. Can it be a problem?

In the previous post I realised that I have done a useless log, In my log I have only "wifi down, rebooting." What kind of more useful information can I log down?

Just to confirm that I also see the white led going off when wifi is lost sometimes. Maybe it is a more serious problem than just the wifi link.

do you have sd card bootable?

yes, do you think it has something to do with it?

mantissa00: ... Signal Noise RX Rate TX Rate -88 dBm 0 dBm 28.9 Mbit/s, MCS 3, 20MHz 21.7 Mbit/s, MCS 2, 20MHz

if I go in the yun luci (advanced panel) I can see the ip of the router with those values: -71 dBm -88 dBm 13.0 Mbit/s, MCS 1, 20MHz 28.9 Mbit/s, MCS 3, 20MHz ...

-88 dBm as Noise is too high, your s/n (Signal-to-noise ratio) is too low ( only 17 dBm) . check your wifi channel spectrum, select less crowded channel.

sonnyyu: why do you think that the wifi low signal makes the system crash?