diff --git a/src/main.cpp b/src/main.cpp
index d8f5d90..e81b731 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -42,14 +42,15 @@ static unsigned long mqttReconnectAt = 0;
 // ---------------------------------------------------------------------------
 
 static void loadConfig() {
-  if (!LittleFS.exists("/config.json")) return;
+  Serial.println("[CFG] loading config");
+  if (!LittleFS.exists("/config.json")) { Serial.println("[CFG] no config file"); return; }
   File f = LittleFS.open("/config.json", "r");
-  if (!f) return;
+  if (!f) { Serial.println("[CFG] failed to open"); return; }
 
   JsonDocument doc;
   DeserializationError err = deserializeJson(doc, f);
   f.close();
-  if (err) return;
+  if (err) { Serial.printf("[CFG] parse error: %s\n", err.c_str()); return; }
 
   if (doc["hostname"].is<const char*>())
     strlcpy(hostname, doc["hostname"], sizeof(hostname));
@@ -72,6 +73,7 @@ static void loadConfig() {
     meters[i].maxDuty      = m["maxD"]    | 0.0f;
     meters[i].currentValue = m["current"] | 0.0f;
   }
+  Serial.printf("[CFG] loaded hostname=%s meters=%d mqtt_en=%d\n", hostname, meterCount, mqttCfg.enabled);
 }
 
 static void saveConfig() {
@@ -98,6 +100,9 @@ static void saveConfig() {
   if (f) {
     serializeJson(doc, f);
     f.close();
+    Serial.printf("[CFG] saved hostname=%s meters=%d mqtt_en=%d\n", hostname, meterCount, mqttCfg.enabled);
+  } else {
+    Serial.println("[CFG] save failed");
   }
 }
 
@@ -110,6 +115,7 @@ static void attachMeters() {
     if (meters[i].pin > 0) {
       ledcSetup(i, PWM_FREQ, PWM_RES);
       ledcAttachPin(meters[i].pin, i);
+      Serial.printf("[PWM] attach ch%d pin%d\n", i, meters[i].pin);
     }
   }
 }
@@ -120,6 +126,7 @@ static void applyMeters() {
     float pct = meters[i].currentValue / 100.0f * meters[i].maxDuty / 100.0f;
     int duty = constrain((int)(pct * 1023), 0, 1023);
     ledcWrite(i, duty);
+    Serial.printf("[PWM] ch%d duty=%d (cur=%.1f maxD=%.1f)\n", i, duty, meters[i].currentValue, meters[i].maxDuty);
   }
 }
 
@@ -131,6 +138,7 @@ static void mqttCallback(char* topic, byte* payload, unsigned int len) {
   String valStr;
   for (unsigned i = 0; i < len; i++) valStr += (char)payload[i];
   float val = valStr.toFloat();
+  Serial.printf("[MQTT] rcvd topic=%s payload=%s\n", topic, valStr.c_str());
 
   // topic format: <prefix>/meter/<idx>/current/set  or  .../maxduty/set
   String t = String(topic);
@@ -146,6 +154,7 @@ static void mqttCallback(char* topic, byte* payload, unsigned int len) {
   String suffix = t.substring(slash);
 
   if (suffix == "/current/set") {
+    Serial.printf("[MQTT] set meter%d current=%.1f\n", idx, val);
     meters[idx].currentValue = val;
     if (meters[idx].pin > 0 && meters[idx].maxDuty > 0) {
       float pct = val / 100.0f * meters[idx].maxDuty / 100.0f;
@@ -153,6 +162,7 @@ static void mqttCallback(char* topic, byte* payload, unsigned int len) {
     }
     saveConfig();
   } else if (suffix == "/maxduty/set") {
+    Serial.printf("[MQTT] set meter%d maxduty=%.1f\n", idx, val);
     meters[idx].maxDuty = constrain(val, 0, 100);
     attachMeters();
     applyMeters();
@@ -165,7 +175,8 @@ static void mqttPublishCurrent(int idx) {
   char topic[128], val[16];
   snprintf(topic, sizeof(topic), "%s/meter/%d/current", mqttCfg.prefix, idx);
   snprintf(val, sizeof(val), "%.1f", meters[idx].currentValue);
-  mqttClient.publish(topic, val, true);
+  bool ok = mqttClient.publish(topic, val, true);
+  Serial.printf("[MQTT] publish topic=%s val=%s ok=%d\n", topic, val, ok);
 }
 
 static void mqttSubscribe() {
@@ -174,13 +185,19 @@ static void mqttSubscribe() {
     char t[128];
     snprintf(t, sizeof(t), "%s/meter/%d/current/set", mqttCfg.prefix, i);
     mqttClient.subscribe(t);
+    Serial.printf("[MQTT] subscribed %s\n", t);
     snprintf(t, sizeof(t), "%s/meter/%d/maxduty/set", mqttCfg.prefix, i);
     mqttClient.subscribe(t);
+    Serial.printf("[MQTT] subscribed %s\n", t);
   }
 }
 
 static bool mqttConnect() {
-  if (!mqttCfg.enabled || strlen(mqttCfg.host) == 0 || strlen(mqttCfg.user) == 0 || strlen(mqttCfg.pass) == 0) return false;
+  if (!mqttCfg.enabled || strlen(mqttCfg.host) == 0 || strlen(mqttCfg.user) == 0 || strlen(mqttCfg.pass) == 0) {
+    Serial.printf("[MQTT] connect skipped en=%d host=%d user=%d pass=%d\n",
+      mqttCfg.enabled, strlen(mqttCfg.host) > 0, strlen(mqttCfg.user) > 0, strlen(mqttCfg.pass) > 0);
+    return false;
+  }
 
   char clientId[32];
   {
@@ -192,13 +209,14 @@ static bool mqttConnect() {
   mqttClient.setServer(mqttCfg.host, mqttCfg.port);
   mqttClient.setCallback(mqttCallback);
 
+  Serial.printf("[MQTT] connecting to %s:%d as %s\n", mqttCfg.host, mqttCfg.port, clientId);
   bool ok = mqttClient.connect(clientId, mqttCfg.user, mqttCfg.pass);
 
   if (ok) {
-    Serial.printf("MQTT connected to %s:%d\n", mqttCfg.host, mqttCfg.port);
+    Serial.printf("[MQTT] connected to %s:%d\n", mqttCfg.host, mqttCfg.port);
     mqttSubscribe();
   } else {
-    Serial.printf("MQTT failed rc=%d\n", mqttClient.state());
+    Serial.printf("[MQTT] failed rc=%d\n", mqttClient.state());
   }
   return ok;
 }
@@ -209,15 +227,17 @@ static void mqttLoop() {
   if (!mqttClient.connected()) {
     unsigned long now = millis();
     if (now > mqttReconnectAt) {
-      // quick TCP probe with short timeout before the blocking MQTT connect
+      Serial.printf("[MQTT] probing %s:%d\n", mqttCfg.host, mqttCfg.port);
       WiFiClient probe;
       bool reachable = probe.connect(mqttCfg.host, mqttCfg.port, 1500);
       probe.stop();
 
       if (reachable) {
+        Serial.println("[MQTT] probe OK, connecting");
         if (mqttConnect()) mqttReconnectAt = 0;
         else mqttReconnectAt = now + 30000;
       } else {
+        Serial.println("[MQTT] probe failed, retry in 30s");
         mqttReconnectAt = now + 30000;
       }
     }
@@ -262,6 +282,7 @@ static String escHtml(const String& s) {
 // ---------------------------------------------------------------------------
 
 static void handleRoot() {
+  Serial.println("[HTTP] GET /");
   String meterRows;
   for (int i = 0; i < meterCount; i++) {
     char maxStr[8], curStr[8];
@@ -364,9 +385,11 @@ static void handleRoot() {
   html += "document.querySelector('select[name=meter_count]').addEventListener('change',function(){this.form.submit();});";
   html += "</script></body></html>";
   server.send(200, "text/html", html);
+  Serial.printf("[HTTP] GET / -> 200 (%u bytes)\n", html.length());
 }
 
 static void handleConfig() {
+  Serial.println("[HTTP] POST /config");
   if (server.hasArg("hostname")) {
     String val = server.arg("hostname");
     val.trim();
@@ -386,8 +409,11 @@ static void handleConfig() {
       strlcpy(mqttCfg.pass, server.arg("mqtt_pass").c_str(), sizeof(mqttCfg.pass));
     if (server.hasArg("mqtt_prefix"))
       strlcpy(mqttCfg.prefix, server.arg("mqtt_prefix").c_str(), sizeof(mqttCfg.prefix));
+    Serial.printf("[HTTP] mqtt enabled host=%s port=%u user=%s prefix=%s\n",
+      mqttCfg.host, mqttCfg.port, mqttCfg.user, mqttCfg.prefix);
   } else {
     mqttCfg.enabled = false;
+    Serial.println("[HTTP] mqtt disabled");
   }
 
   int newCount = meterCount;
@@ -407,6 +433,8 @@ static void handleConfig() {
 
   meterCount = newCount;
   memcpy(meters, newMeters, sizeof(meters));
+  for (int i = 0; i < meterCount; i++)
+    Serial.printf("[HTTP] meter%d pin=%d maxD=%.1f cur=%.1f\n", i, meters[i].pin, meters[i].maxDuty, meters[i].currentValue);
 
   saveConfig();
   attachMeters();
@@ -421,11 +449,12 @@ static void handleConfig() {
 }
 
 static void handleSet() {
-  if (!server.hasArg("i") || !server.hasArg("v")) { server.send(400); return; }
+  if (!server.hasArg("i") || !server.hasArg("v")) { server.send(400); Serial.println("[HTTP] GET /set missing args"); return; }
   int idx = server.arg("i").toInt();
   float val = server.arg("v").toFloat();
-  if (idx < 0 || idx >= meterCount) { server.send(400); return; }
+  if (idx < 0 || idx >= meterCount) { server.send(400); Serial.printf("[HTTP] GET /set bad idx=%d\n", idx); return; }
   meters[idx].currentValue = val;
+  Serial.printf("[HTTP] GET /set meter%d=%.1f\n", idx, val);
   if (meters[idx].pin > 0 && meters[idx].maxDuty > 0) {
     float pct = val / 100.0f * meters[idx].maxDuty / 100.0f;
     int duty = constrain((int)(pct * 1023), 0, 1023);
@@ -450,6 +479,7 @@ static void startServer() {
 
 void setup() {
   Serial.begin(115200);
+  Serial.println("\n\n=== M1730 boot ===");
   LittleFS.begin(true);
 
   loadConfig();
@@ -457,6 +487,7 @@ void setup() {
   attachMeters();
   applyMeters();
 
+  Serial.println("[WIFI] starting WiFiManager");
   WiFiManager wm;
   wm.setTitle("M1730");
 
@@ -467,17 +498,18 @@ void setup() {
   });
 
   if (!wm.autoConnect("M1730")) {
-    Serial.println("WiFi failed, restarting");
+    Serial.println("[WIFI] failed, restarting");
     ESP.restart();
   }
+  Serial.printf("[WIFI] connected, IP: %s\n", WiFi.localIP().toString().c_str());
 
   strlcpy(hostname, hostnameParam.getValue(), sizeof(hostname));
   saveConfig();
   startServer();
   startMDNS();
-  mqttReconnectAt = 0; // handshake deferred to mqttLoop in loop()
+  mqttReconnectAt = 0;
 
-  Serial.printf("Board address: http://%s.local or http://%s\n",
+  Serial.printf("[BOOT] ready at http://%s.local or http://%s\n",
                 hostname, WiFi.localIP().toString().c_str());
 }