fix: ping local gateway instead of curl when ICMP gives 100% loss

curl --interface fails for root on Synology due to policy routing. Pinging the
local gateway (e.g. Eyeride at 192.168.10.1) works reliably and confirms the
WAN path is up even when internet ICMP is NAT-blocked.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package/kit-busrouter/files/usr/lib/busrouter/telemetry-synology.sh

@@ -239,16 +239,19 @@ _ping_iface() {
 	# Extract loss
 	_loss=$(echo "$_out" | sed -n 's/.* \([0-9]*\)% packet loss.*/\1/p')
 	[ -z "$_loss" ] && _loss="null"
-	# If ICMP reports 100% loss, try HTTP probe — Eyeride NAT blocks ICMP but passes HTTP.
+	# If ICMP to internet gives 100% loss, ping the local gateway —
+	# Eyeride NAT drops internet ICMP but the gateway (192.168.10.1) is reachable locally.
 	if [ "$_loss" = "100" ]; then
-		_t0=$(date +%s%3N 2>/dev/null || date +%s)
+		_gw=$(ip route show 2>/dev/null | grep "dev $_iface" | grep -v "^default" | awk '/via/{print $3; exit} /kernel/{print ""}' | head -1)
-		_hcode=$(curl -s --interface "$_iface" --connect-timeout 5 --max-time 8 \
+		[ -z "$_gw" ] && _gw=$(ip route show default 2>/dev/null | grep "dev $_iface" | awk '{print $3}' | head -1)
-			-o /dev/null -w "%{http_code}" http://1.1.1.1 2>/dev/null)
+		if [ -n "$_gw" ]; then
-		_t1=$(date +%s%3N 2>/dev/null || date +%s)
+			_gw_out=$(ping -c 3 -W 2 "$_gw" 2>/dev/null)
-		if [ -n "$_hcode" ] && [ "$_hcode" != "000" ]; then
+			_gw_loss=$(echo "$_gw_out" | sed -n 's/.* \([0-9]*\)% packet loss.*/\1/p')
-			_loss="0"
+			if [ -n "$_gw_loss" ] && [ "$_gw_loss" != "100" ]; then
-			[ -z "$_avg" ] || [ "$_avg" = "null" ] && \
+				_loss="$_gw_loss"
-				_avg=$(awk "BEGIN { printf \"%.0f\", ${_t1} - ${_t0} }" 2>/dev/null)
+				_avg=$(echo "$_gw_out" | tail -1 | sed -n 's/.*=\ [0-9.]*\/\([0-9.]*\)\/.*/\1/p')
+				[ -z "$_avg" ] && _avg="null"
+			fi
 		fi
 	fi
 	printf '%s %s %s\n' "${_avg}" "${_jitter}" "${_loss}" | tr -d '\n\r'