diff --git a/include/wordclock_constants.h b/include/wordclock_constants.h
index 5cd9ad4..03b8b4d 100644
--- a/include/wordclock_constants.h
+++ b/include/wordclock_constants.h
@@ -72,7 +72,7 @@
 #define BUILD_YEAR (__DATE__ + 7)                  // Will expand to current year at compile time as string.
 #define NTP_MININUM_RX_YEAR (atoi(BUILD_YEAR) - 1) // Will expand to current year minus one at compile time.
 #define NTP_START_YEAR (1900)                      // NTP minimum year is 1900
-#define NTP_UPDATE_PERIOD_S (12 * 3600)            // 12h period between updates
+#define NTP_UPDATE_PERIOD_S (6 * 3600)             // 6h period between NTP updates
 #define NTP_RETRY_DELAY_US (10 * 1000 * 1000)      // 10s retry delay time between failed NTP requests
 #define NTP_MAX_OFFLINE_TIME_S (7 * 24 * 3600)     // Watchdog value, maxmimum offline time before a restart is triggered
 
diff --git a/src/connectivity/time_manager.cpp b/src/connectivity/time_manager.cpp
index 5bca332..7141d27 100644
--- a/src/connectivity/time_manager.cpp
+++ b/src/connectivity/time_manager.cpp
@@ -69,7 +69,7 @@ NtpUpdateState TimeManager::ntp_time_update()
     }
 
     // Check if it is time for a NTP sync.
-    if ((_tm_state != TM_INITIAL_SYNC) && (_tm_state != TM_RETRY_SYNC) && ((system_get_time() - _ntp_sync_timestamp_us) <= (_ntp_update_period_s * 1000000)))
+    if ((_tm_state != TM_INITIAL_SYNC) && (_tm_state != TM_RETRY_SYNC) && (((system_get_time() - _ntp_sync_timestamp_us) / 1000000) <= _ntp_update_period_s))
     {
         return NTP_UPDATE_TOO_EARLY;
     }
@@ -175,7 +175,7 @@ void TimeManager::_set_up_timer_isr(void)
     if (ITimer.attachInterruptInterval(PERIOD_CLOCK_UPDATE_US, TimerHandler))
     {
         _tm_state = TM_NORMAL;
-        logger.log_string(String("Timer ISR was initialized!"));
+        logger.log_string(String("Timer ISR was attached successfully!"));
     }
     else
     {
@@ -195,7 +195,7 @@ void TimeManager::_set_up_ntp(void)
         // set up NTP server and timezone at init
         configTime(_tz, _ntp_server);
         _tm_state = TM_INITIAL_SYNC;
-        logger.log_string(String("NTP server was initialized!"));
+        logger.log_string(String("NTP server connection was set up successfully!"));
     }
     else
     {
diff --git a/src/wordclock_esp8266.cpp b/src/wordclock_esp8266.cpp
index 2fa2f06..a2e5aa3 100644
--- a/src/wordclock_esp8266.cpp
+++ b/src/wordclock_esp8266.cpp
@@ -251,9 +251,6 @@ void loop()
     if ((current_time_us - last_heartbeat_us) >= PERIOD_HEARTBEAT_US)
     {
         send_heartbeat(); // send heartbeat update
-
-        tm_mgr.log_time(); // TODO rm
-
         last_heartbeat_us = system_get_time();
         delay(10);
     }
@@ -283,7 +280,10 @@ void loop()
 
     if ((current_time_us - last_time_update_us) >= PERIOD_TIME_UPDATE_US)
     {
-        tm_mgr.ntp_time_update(); // NTP time update
+        if (tm_mgr.ntp_time_update() == NTP_UPDATE_OK) // NTP time update
+        {
+            logger.log_string("NTP sync successful!");
+        }
 
         if (tm_mgr.ntp_update_failed_prolonged() == true)
         {