Problems with WLAN connectivity - solved

sdetweil

@rkorell awesome post, great info!

rkorell

In addition: If somebody is interested in the scripts and system-services definitions for own purposes - give me a ping and I will share this for sure…

Regards,
Ralf

schlomm

@rkorell Thanks for your Insights! Interesting!
One question: How you got the idea that the issue is caused by power/energy circumstances?
Are there any specific logs with those information?

And yes - it would be great to get an idea of your scripts :)

rkorell

Dear @schlomm ,
I initially had no clue at all regarding root cause :-)
And the finding “undervoltage” was never expected but came out off my logfiles.

After a LOT of tinkering and playing with syptomatic “solutions” system kept to be unstable so I decided to dig in and do some logging to identify root cause.

For this I wrote a shellscript and installed a system service which collects this data every five minutes.

shellscript:

sudo nano /usr/local/bin/wlan-diagnose.sh

content:

#!/bin/bash
LOGFILE="/var/log/wlan-diagnose.log"
DATE=$(date '+%a %d %b %H:%M:%S %Z %Y')
WLAN_IF="wlan0"

echo "===== $DATE =====" >> $LOGFILE

# IP-Adresse
echo "--- IP-Adresse ---" >> $LOGFILE
ip addr show $WLAN_IF >> $LOGFILE 2>&1

# Link-Status
echo "--- Link Status ---" >> $LOGFILE
iw dev $WLAN_IF link >> $LOGFILE 2>&1

# Default Route
echo "--- Routing ---" >> $LOGFILE
ip route >> $LOGFILE 2>&1

# Wpa_supplicant Status
echo "--- wpa_supplicant ---" >> $LOGFILE
systemctl status wpa_supplicant --no-pager >> $LOGFILE 2>&1

# Letzte wpa_supplicant Logs
echo "--- wpa_supplicant journal (letzte 20 Zeilen) ---" >> $LOGFILE
journalctl -u wpa_supplicant -n 20 --no-pager >> $LOGFILE 2>&1

# Kernel/Treiber Logs
echo "--- dmesg wlan0 ---" >> $LOGFILE
dmesg | tail -n 20 >> $LOGFILE 2>&1

# Ping-Test
PING_TARGET="8.8.8.8"
ping -I $WLAN_IF -c3 -W3 $PING_TARGET >> $LOGFILE 2>&1

echo "" >> $LOGFILE

set as executable:

sudo chmod +x /usr/local/bin/wlan-diagnose.sh

systemd-timer for this diagnosis script:

sudo nano /etc/systemd/system/wlan-diagnose.timer

content:

[Unit]
Description=WLAN Diagnose alle 5 Minuten

[Timer]
OnBootSec=1min
OnUnitActiveSec=5min
Persistent=true

[Install]
WantedBy=timers.target

service file:

sudo nano /etc/systemd/system/wlan-diagnose.service

content:

[Unit]
Description=WLAN Diagnose Service

[Service]
Type=oneshot
ExecStart=/usr/local/bin/wlan-diagnose.sh

activate the service:

sudo systemctl daemon-reload
sudo systemctl enable --now wlan-diagnose.timer

Created logfile: /var/log/wlan-diagnose.log

possible command for filtering for errors:

grep -i "fail\|error\|disconnect" /var/log/wlan-diagnose.log

in my personal case directly after starting the service the undervoltage warnings appeared in the logfile:

Sep 24 19:23:02 MagicMirrorPi5 wpa_supplicant[702]: wlan0: CTRL-EVENT-CONNECTED - Connection to f8:bc:0e:51:50:48 completed [id=0 id_str=] Sep 24 19:23:02 MagicMirrorPi5 wpa_supplicant[702]: bgscan simple: Failed to enable signal strength monitoring --- dmesg wlan0 --- [ 385.672898] hwmon hwmon4: Voltage normalised [ 399.780700] hwmon hwmon4: Undervoltage detected! [ 401.796721] hwmon hwmon4: Voltage normalised [ 403.812728] hwmon hwmon4: Undervoltage detected! [ 405.831888] hwmon hwmon4: Voltage normalised [ 425.988994] hwmon hwmon4: Undervoltage detected! [ 428.008109] hwmon hwmon4: Voltage normalised [ 434.052979] hwmon hwmon4: Undervoltage detected! [ 438.087587] hwmon hwmon4: Voltage normalised [ 442.117090] hwmon hwmon4: Undervoltage detected! [ 444.133104] hwmon hwmon4: Voltage normalised [ 452.198182] hwmon hwmon4: Undervoltage detected! [ 454.213171] hwmon hwmon4: Voltage normalised [ 470.341318] hwmon hwmon4: Undervoltage detected! [ 478.405369] hwmon hwmon4: Voltage normalised [ 488.485467] hwmon hwmon4: Undervoltage detected! [ 490.505469] hwmon hwmon4: Voltage normalised [ 514.693689] hwmon hwmon4: Undervoltage detected! [ 516.709733] hwmon hwmon4: Voltage normalised [ 520.744884] hwmon hwmon4: Undervoltage detected! PING 8.8.8.8 (8.8.8.8) from 172.23.56.157 wlan0: 56(84) bytes of data. 64 bytes from 8.8.8.8: icmp_seq=1 ttl=116 time=13.2 ms 64 bytes from 8.8.8.8: icmp_seq=2 ttl=116 time=33.6 ms 64 bytes from 8.8.8.8: icmp_seq=3 ttl=116 time=27.5 ms --- 8.8.8.8 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2003ms rtt min/avg/max/mdev = 13.220/24.756/33.576/8.529 ms

So I had identified my root cause with first strike.

In the meantime (today) I had severe additional problems (also “identified” by this mentioned log) - but this was a kernel/device driver problem which I cannot solve today.
But this leads to a modified recovery script because the version from yesterday only tried to restart the WPA_Supplicant which was not sufficient for my problem today.

If you are interested in, this is the recovery script:

#!/bin/bash
# wlan-recovery.sh
# Prüft WLAN-Verbindung und startet wpa_supplicant / Interface bei Ausfall neu

LOGFILE="/var/log/wlan-recovery.log"
WLAN_IF="wlan0"
PING_TARGET="8.8.8.8"
DATE=$(date '+%a %d %b %H:%M:%S %Z %Y')

# 1. Power save prüfen & ggf. deaktivieren
PS=$(iw dev $WLAN_IF get power_save)
if [ "$PS" = "Power save: on" ]; then
    echo "$DATE: Power Save ist ON → deaktiviere" >> $LOGFILE
    iw dev $WLAN_IF set power_save off
fi

# 2. Verbindung prüfen
ping -I $WLAN_IF -c1 -W3 $PING_TARGET > /dev/null 2>&1
if [ $? -ne 0 ]; then
    echo "$DATE: Keine Verbindung. Versuche wpa_supplicant restart..." >> $LOGFILE
    systemctl restart wpa_supplicant
    sleep 5

    ping -I $WLAN_IF -c1 -W3 $PING_TARGET > /dev/null 2>&1
    if [ $? -ne 0 ]; then
        echo "$DATE: Verbindung immer noch nicht da. Interface + Treiber toggle..." >> $LOGFILE
        
        # Interface herunterfahren
        ip link set $WLAN_IF down
        sleep 2
        
        # Treiber neu laden
        modprobe -r brcmfmac
        sleep 2
        modprobe brcmfmac
        sleep 2

        # Interface wieder hochfahren
        ip link set $WLAN_IF up
        sleep 5

        ping -I $WLAN_IF -c1 -W3 $PING_TARGET > /dev/null 2>&1
        if [ $? -ne 0 ]; then
            echo "$DATE: Wiederherstellung fehlgeschlagen." >> $LOGFILE
        else
            echo "$DATE: Verbindung wiederhergestellt nach Interface + Treiber reload." >> $LOGFILE
        fi
    else
        echo "$DATE: Verbindung wiederhergestellt nach wpa_supplicant restart." >> $LOGFILE
    fi
else
    echo "$DATE: Verbindung ok." >> $LOGFILE
fi

Hope this helps you.
Do not hesitate to ask for futher information …

Warmest regards,
Ralf

rkorell

addition:
the recovery script is: /usr/local/bin/wlan-recovery.sh

set executable:

sudo chmod +x /usr/local/bin/wlan-recovery.sh

Systemd-Service

sudo nano /etc/systemd/system/wlan-recovery.service

content:

[Unit]
Description=WLAN Recovery Script
After=network.target

[Service]
Type=oneshot
ExecStart=/usr/local/bin/wlan-recovery.sh

timer:

sudo nano /etc/systemd/system/wlan-recovery.timer

content:

[Unit]
Description=Run WLAN Recovery every 5 minutes

[Timer]
OnBootSec=1min
OnUnitActiveSec=5min
Persistent=true

[Install]
WantedBy=timers.target

activate this service:

sudo systemctl daemon-reload
sudo systemctl enable --now wlan-recovery.timer

logfile: /var/log/wlan-recovery.log

schlomm

@rkorell Thanks for all these detailed Information! I’ll setup your scripts on my MagicMirror Instances - I have 6 different ones to manage and at least one has some weird problems - maybe also relating to power issues.

Thanks und Vielen Dank :)

rkorell

@schlomm Sehr gern und VIEL ERFOLG!

melde Dich, wenn Du noch was benötigst.
Ralf