Problems with WLAN connectivity - solved

[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

[rkorell]

Dear @schlomm , team,

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

[rkorell]

In addition: It’s possible that the old recovery script was part of my problems - due to the above mentioned ping problem.
For this reason I’ve edited my earlier post and deleted the content of the script.
I’ve added an “edit note” instead.
Sorry for confusion and any inconvenience!

Regards,
Ralf