Regards,
Ralf

as I learned today sometimes system limitations are hard and leads to unwanted results.
I even got more serioous trouble with my pi and his WIFI so I had to dig in deeper.
The aproach until now - because of “growing” up - is a “recovery” and a “diagnose” part.
This leads to - surprise, surprise :-) - inconsistent data and so dignosis is merely impossible.
For this reason I converged both approches into one script and implemented a 4-stages error-handling and consecutive escalation (until reboot).

At this stage i had to recognize: almost EVERY test results immediatly in an error at stage 1 (ping) and was resolved at stage 2 (L2/L3 - ICMP problem – checking status of wlan interface).
To identify root cause for this I - again - dig down deeply (ChatGPT was NOT that helpful!) and found: At systemd level (on my system!?) ping is not in PATH !!!
So a fully qualified call solved this problem - and most of my “problems” are solved !

If you are using “ping”, too and stuck in problems in scripts - keep this in mind: “usr/bin/ping” might be really helpful for you.

If you are interested in, here my current recovery-script - including some useful logging information:

/usr/local/bin/wlan-recovery.sh
#!/bin/bash
# ============================================================================
# WLAN Recovery Script (Monolithische Version)
# Autor: Dr.  Ralf Korell, MD 
# Datum: 2025-10-07
#
# Dieses Script wird per systemd-Timer regelmäßig aufgerufen.
# Es prüft die WLAN-Verbindung in mehreren Stufen und führt nur dann
# Recovery-Aktionen aus, wenn wirklich eine Unterbrechung vorliegt.
#
# Features:
#   - Mehrstufige Diagnose (Ping, iw, IP, Route)
#   - Schutz vor Fehlalarmen und Selbstabschüssen
#   - SSH/VNC-Safe-Mode (keine Unterbrechung aktiver Sessions)
#   - Logrotation + Statistikdatei
# ============================================================================

# === Konfiguration ==========================================================
LOGFILE="/var/log/wlan-recovery.log"
STATSFILE="/var/log/wlan-recovery.stats"
MAX_LOG_SIZE=50000              # ~50 KB, dann Logrotation
PING_TARGET="172.23.56.1"
MAX_CONSECUTIVE_FAILS=2         # bevor Recovery startet
COOLDOWN_FILE="/tmp/wlan-recovery.cooldown"
COOLDOWN_MINUTES=5

# interne Speicherorte (nicht verändern)
STATEFILE="/tmp/wlan-recovery.state"
DATE_NOW=$(date "+%Y-%m-%d %H:%M:%S")

# === Hilfsfunktionen ========================================================

log() {
    echo "$DATE_NOW: $1" | tee -a "$LOGFILE"
}

rotate_log() {
    if [ -f "$LOGFILE" ] && [ $(wc -c <"$LOGFILE") -gt $MAX_LOG_SIZE ]; then
        mv "$LOGFILE" "$LOGFILE.old"
        echo "$DATE_NOW: Log rotated." > "$LOGFILE"
    fi
}

increment_stat() {
    local key="$1"
    local value
    value=$(grep "^$key=" "$STATSFILE" 2>/dev/null | cut -d= -f2)
    value=$((value + 1))
    grep -v "^$key=" "$STATSFILE" 2>/dev/null > "${STATSFILE}.tmp"
    echo "$key=$value" >> "${STATSFILE}.tmp"
    mv "${STATSFILE}.tmp" "$STATSFILE"
}

cooldown_active() {
    if [ -f "$COOLDOWN_FILE" ]; then
        local last=$(date -r "$COOLDOWN_FILE" +%s)
        local now=$(date +%s)
        local diff=$(( (now - last) / 60 ))
        [ $diff -lt $COOLDOWN_MINUTES ]
    else
        return 1
    fi
}

start_cooldown() {
    touch "$COOLDOWN_FILE"
}

ssh_or_vnc_active() {
    ss -tn state established | grep -Eq '(:22|:5900)'
}

# === Diagnosefunktionen =====================================================

is_connected_l2() {
    iw dev wlan0 link 2>/dev/null | grep -q "Connected to"
}

has_ip_l3() {
    ip -4 addr show wlan0 2>/dev/null | grep -q "inet "
}

has_route() {
    ip route get "$PING_TARGET" 2>/dev/null | grep -q "dev wlan0"
}

ping_ok() {
    /usr/bin/ping -I wlan0 -c 3 -W 2 "$PING_TARGET" >/dev/null 2>&1
}

# === Hauptlogik =============================================================

rotate_log

# Init Statsfile falls nicht vorhanden
[ -f "$STATSFILE" ] || echo -e "success=0\nrecoveries=0\nfailures=0" > "$STATSFILE"

# Lese bisherigen Fehlerzähler
fails=0
[ -f "$STATEFILE" ] && fails=$(cat "$STATEFILE")

# Diagnose
if ping_ok; then
    log "Ping erfolgreich. WLAN funktioniert."
    echo 0 > "$STATEFILE"
    increment_stat "success"
    exit 0
fi

# Wenn Ping fehlschlägt → weitere Prüfungen
log "Ping fehlgeschlagen → erweiterte Diagnose..."

if is_connected_l2 && has_ip_l3 && has_route; then
    log "L2/L3 ok → ICMP-Problem (kein Recovery)."
    increment_stat "failures"
    echo 0 > "$STATEFILE"
    exit 0
fi

# Hier gilt: echte Verbindung gestört
fails=$((fails + 1))
echo "$fails" > "$STATEFILE"

if [ $fails -lt $MAX_CONSECUTIVE_FAILS ]; then
    log "Erster Fehler ($fails/$MAX_CONSECUTIVE_FAILS) → Beobachten..."
    increment_stat "failures"
    exit 0
fi

# Wenn Cooldown läuft → überspringen
if cooldown_active; then
    log "Cooldown aktiv → Recovery übersprungen."
    exit 0
fi

# === Recovery-Stufen ========================================================

if ssh_or_vnc_active; then
    log "SSH/VNC aktiv → keine Recovery ausgeführt, nur geloggt."
    increment_stat "failures"
    exit 0
fi

log "Verbindung tatsächlich gestört → Recovery-Prozess gestartet."
increment_stat "recoveries"

# Stufe 1: sanfte Reassoziation
log "→ Stufe 1: wpa_supplicant Reassoziation..."
wpa_cli -i wlan0 reassociate >/dev/null 2>&1
sleep 5
if ping_ok; then
    log "Reassoziation erfolgreich."
    echo 0 > "$STATEFILE"
    start_cooldown
    exit 0
fi

# Stufe 2: Interface Toggle
log "→ Stufe 2: Interface Toggle..."
ip link set wlan0 down
sleep 2
ip link set wlan0 up
sleep 8
if ping_ok; then
    log "Interface Toggle erfolgreich."
    echo 0 > "$STATEFILE"
    start_cooldown
    exit 0
fi

# Stufe 3: Treiber-Reload
log "→ Stufe 3: Treiber-Reload..."
modprobe -r brcmfmac && modprobe brcmfmac
sleep 10
if ping_ok; then
    log "Treiber-Reload erfolgreich."
    echo 0 > "$STATEFILE"
    start_cooldown
    exit 0
fi

# Wenn alles fehlschlägt
log "Alle Recovery-Stufen fehlgeschlagen → Fehler bleibt bestehen."
increment_stat "failures"
start_cooldown
exit 1

[EDIT: in script above: changed ping count from -c 1 to -c 3 in:
/usr/bin/ping -I wlan0 -c 1 -W 2 “$PING_TARGET” >/dev/null 2>&1
]
Warmest regards,
Ralf

• melde Dich, wenn Du noch was benötigst.
  Ralf

Thanks und Vielen Dank :)

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

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.

[EDIT - Sep, 8th, 2025: deleted old recovery script because usage of ping without qualified path produced an error by the script itself. For this reason the script is not as useful as I thought. Sorry for confusion! ]

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

Warmest regards,
Ralf

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

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