diff --git a/sonoff/_changelog.ino b/sonoff/_changelog.ino
index ad30eb7f7..a08bea0fc 100644
--- a/sonoff/_changelog.ino
+++ b/sonoff/_changelog.ino
@@ -7,6 +7,7 @@
  * Remove command SetOption62 as it's functionality is replaced by user changing the device template (#5255)
  * Add property LinkCount to state and status 11 message representing number of Wifi Link re-connections
  * Add property MqttCount to status 6 message representing number of Mqtt re-connections
+ * Add property Downtime to state and status 11 message representing the duration of wifi connection loss
  *
  * 6.4.1.16 20190211
  * Initial support for online template change using command Template or GUI Configure Other (#5177)
diff --git a/sonoff/i18n.h b/sonoff/i18n.h
index d2e15e475..7340a3484 100644
--- a/sonoff/i18n.h
+++ b/sonoff/i18n.h
@@ -54,6 +54,7 @@
 #define D_JSON_DISTANCE "Distance"
 #define D_JSON_DNSSERVER "DNSServer"
 #define D_JSON_DONE "Done"
+#define D_JSON_DOWNTIME "Downtime"
 #define D_JSON_ECO2 "eCO2"
 #define D_JSON_EMPTY "Empty"
 #define D_JSON_ENDDST "EndDST"           // End Daylight Savings Time
diff --git a/sonoff/sonoff.ino b/sonoff/sonoff.ino
index 26198507b..e54c23260 100755
--- a/sonoff/sonoff.ino
+++ b/sonoff/sonoff.ino
@@ -1775,8 +1775,8 @@ void MqttShowState(void)
     MqttShowPWMState();
   }
 
-  snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s,\"" D_JSON_WIFI "\":{\"" D_JSON_AP "\":%d,\"" D_JSON_SSID "\":\"%s\",\"" D_JSON_BSSID "\":\"%s\",\"" D_JSON_CHANNEL "\":%d,\"" D_JSON_RSSI "\":%d,\"" D_JSON_LINK_COUNT "\":%d}}"),
-    mqtt_data, Settings.sta_active +1, Settings.sta_ssid[Settings.sta_active], WiFi.BSSIDstr().c_str(), WiFi.channel(), WifiGetRssiAsQuality(WiFi.RSSI()), WifiLinkCount());
+  snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s,\"" D_JSON_WIFI "\":{\"" D_JSON_AP "\":%d,\"" D_JSON_SSID "\":\"%s\",\"" D_JSON_BSSID "\":\"%s\",\"" D_JSON_CHANNEL "\":%d,\"" D_JSON_RSSI "\":%d,\"" D_JSON_LINK_COUNT "\":%d,\"" D_JSON_DOWNTIME "\":\"%s\"}}"),
+    mqtt_data, Settings.sta_active +1, Settings.sta_ssid[Settings.sta_active], WiFi.BSSIDstr().c_str(), WiFi.channel(), WifiGetRssiAsQuality(WiFi.RSSI()), WifiLinkCount(), WifiDowntime().c_str());
 }
 
 bool MqttShowSensor(void)
diff --git a/sonoff/support_rtc.ino b/sonoff/support_rtc.ino
index 12a4d89ec..5c9f9e2b4 100644
--- a/sonoff/support_rtc.ino
+++ b/sonoff/support_rtc.ino
@@ -87,6 +87,23 @@ String GetTimeZone(void)
   return String(tz);  // -03:45
 }
 
+String GetDuration(uint32_t time)
+{
+  char dt[16];
+
+  TIME_T ut;
+  BreakTime(time, ut);
+
+  // "P128DT14H35M44S" - ISO8601:2004 - https://en.wikipedia.org/wiki/ISO_8601 Durations
+//  snprintf_P(dt, sizeof(dt), PSTR("P%dDT%02dH%02dM%02dS"), ut.days, ut.hour, ut.minute, ut.second);
+
+  // "128 14:35:44" - OpenVMS
+  // "128T14:35:44" - Tasmota
+  snprintf_P(dt, sizeof(dt), PSTR("%dT%02d:%02d:%02d"), ut.days, ut.hour, ut.minute, ut.second);
+
+  return String(dt);  // 128T14:35:44
+}
+
 String GetDT(uint32_t time)
 {
   // "2017-03-07T11:08:02" - ISO8601:2004
@@ -155,37 +172,24 @@ String GetTime(int type)
   return String(stime);  // Thu Nov 01 11:41:02 2018
 }
 
+uint32_t UpTime(void)
+{
+  if (restart_time) {
+    return utc_time - restart_time;
+  } else {
+    return uptime;
+  }
+}
+
 String GetUptime(void)
 {
-  char dt[16];
-
-  TIME_T ut;
-
-  if (restart_time) {
-    BreakTime(utc_time - restart_time, ut);
-  } else {
-    BreakTime(uptime, ut);
-  }
-
-  // "P128DT14H35M44S" - ISO8601:2004 - https://en.wikipedia.org/wiki/ISO_8601 Durations
-//  snprintf_P(dt, sizeof(dt), PSTR("P%dDT%02dH%02dM%02dS"), ut.days, ut.hour, ut.minute, ut.second);
-
-  // "128 14:35:44" - OpenVMS
-  // "128T14:35:44" - Tasmota
-  snprintf_P(dt, sizeof(dt), PSTR("%dT%02d:%02d:%02d"), ut.days, ut.hour, ut.minute, ut.second);
-
-  return String(dt);  // 128T14:35:44
+  return GetDuration(UpTime());
 }
 
 uint32_t GetMinutesUptime(void)
 {
   TIME_T ut;
-
-  if (restart_time) {
-    BreakTime(utc_time - restart_time, ut);
-  } else {
-    BreakTime(uptime, ut);
-  }
+  BreakTime(UpTime(), ut);
 
   return (ut.days *1440) + (ut.hour *60) + ut.minute;
 }
diff --git a/sonoff/support_wifi.ino b/sonoff/support_wifi.ino
index ba3f81ac8..c394005a1 100644
--- a/sonoff/support_wifi.ino
+++ b/sonoff/support_wifi.ino
@@ -49,7 +49,9 @@ using namespace axTLS;
 */
 #include <ESP8266WiFi.h>            // Wifi, MQTT, Ota, WifiManager
 
-uint16_t wifi_link_count = 0;
+uint32_t wifi_last_event = 0;       // Last wifi connection event
+uint32_t wifi_downtime = 0;         // Wifi down duration
+uint16_t wifi_link_count = 0;       // Number of wifi re-connect
 uint8_t wifi_counter;
 uint8_t wifi_retry_init;
 uint8_t wifi_retry;
@@ -346,14 +348,21 @@ uint16_t WifiLinkCount()
   return wifi_link_count;
 }
 
+String WifiDowntime()
+{
+  return GetDuration(wifi_downtime);
+}
+
 void WifiSetState(uint8_t state)
 {
   if (state == global_state.wifi_down) {
     if (state) {
       rules_flag.wifi_connected = 1;
       wifi_link_count++;
+      wifi_downtime += UpTime() - wifi_last_event;
     } else {
       rules_flag.wifi_disconnected = 1;
+      wifi_last_event = UpTime();
     }
   }
   global_state.wifi_down = state ^1;