diff --git a/usermods/deep_sleep/deep_sleep.cpp b/usermods/deep_sleep/deep_sleep.cpp
index 65cebc5e..cff40f86 100644
--- a/usermods/deep_sleep/deep_sleep.cpp
+++ b/usermods/deep_sleep/deep_sleep.cpp
@@ -156,7 +156,7 @@ class DeepSleepUsermod : public Usermod {
         delay(1000);    // just in case: give user a short ~10s window to turn LEDs on in UI (delaycounter is 10 by default)
         return;
       }
-      if (powerup == false && delaycounter) { // delay sleep in case a preset is being loaded and turnOnAtBoot is disabled (handleIO() does enable offMode temporarily in this case)
+      if (powerup == false && delaycounter) { // delay sleep in case a preset is being loaded and turnOnAtBoot is disabled (beginStrip() / handleIO() does enable offMode temporarily in this case)
         delaycounter--;
         if (delaycounter == 1 && offMode) { // force turn on, no matter the settings (device is bricked if user set sleepDelay=0, no bootup preset and turnOnAtBoot=false)
           if (briS == 0) bri = 10; // turn on and set low brightness to avoid automatic turn off
diff --git a/wled00/button.cpp b/wled00/button.cpp
index f6a07f51..d544dd73 100644
--- a/wled00/button.cpp
+++ b/wled00/button.cpp
@@ -367,24 +367,29 @@ void handleIO()
 
   // if we want to control on-board LED (ESP8266) or relay we have to do it here as the final show() may not happen until
   // next loop() cycle
-  if (strip.getBrightness()) {
+  handleOnOff();
+}
+
+void handleOnOff(bool forceOff)
+{
+  if (strip.getBrightness() && !forceOff) {
     lastOnTime = millis();
     if (offMode) {
       BusManager::on();
       if (rlyPin>=0) {
-        pinMode(rlyPin, rlyOpenDrain ? OUTPUT_OPEN_DRAIN : OUTPUT);
-        digitalWrite(rlyPin, rlyMde);
-        delay(50); // wait for relay to switch and power to stabilize
+        // note: pinMode is set in first call to handleOnOff(true) in beginStrip()
+        digitalWrite(rlyPin, rlyMde); // set to on state
+        delay(RELAY_DELAY); // let power stabilize before sending LED data (#346 #812 #3581 #3955)
       }
       offMode = false;
     }
-  } else if (millis() - lastOnTime > 600 && !strip.needsUpdate()) {
+  } else if ((millis() - lastOnTime > 600 && !strip.needsUpdate()) || forceOff) {
     // for turning LED or relay off we need to wait until strip no longer needs updates (strip.trigger())
     if (!offMode) {
       BusManager::off();
       if (rlyPin>=0) {
+        digitalWrite(rlyPin, !rlyMde); // set output before disabling high-z state to avoid output glitches
         pinMode(rlyPin, rlyOpenDrain ? OUTPUT_OPEN_DRAIN : OUTPUT);
-        digitalWrite(rlyPin, !rlyMde);
       }
       offMode = true;
     }
diff --git a/wled00/const.h b/wled00/const.h
index 9fa85dda..50eefe18 100644
--- a/wled00/const.h
+++ b/wled00/const.h
@@ -114,6 +114,8 @@ static_assert(WLED_MAX_BUSSES <= 32, "WLED_MAX_BUSSES exceeds hard limit");
   #endif
 #endif
 
+#define RELAY_DELAY 50 // delay in ms between switching on relay and sending data to LEDs
+
 #if defined(ESP8266) || defined(CONFIG_IDF_TARGET_ESP32S2)
 #define WLED_MAX_COLOR_ORDER_MAPPINGS 5
 #else
diff --git a/wled00/fcn_declare.h b/wled00/fcn_declare.h
index 24c13aae..3081a493 100644
--- a/wled00/fcn_declare.h
+++ b/wled00/fcn_declare.h
@@ -20,6 +20,7 @@ void longPressAction(uint8_t b=0);
 void doublePressAction(uint8_t b=0);
 bool isButtonPressed(uint8_t b=0);
 void handleButton();
+void handleOnOff(bool forceOff = false);
 void handleIO();
 void IRAM_ATTR touchButtonISR();
 
diff --git a/wled00/wled.cpp b/wled00/wled.cpp
index bb1befcd..df9a5833 100644
--- a/wled00/wled.cpp
+++ b/wled00/wled.cpp
@@ -591,6 +591,10 @@ void WLED::beginStrip()
   strip.setShowCallback(handleOverlayDraw);
   doInitBusses = false;
 
+  // init offMode and relay
+  offMode = false;   // init to on state to allow proper relay init
+  handleOnOff(true); // init relay and force off
+
   if (turnOnAtBoot) {
     if (briS > 0) bri = briS;
     else if (bri == 0) bri = 128;
@@ -606,7 +610,8 @@ void WLED::beginStrip()
     }
     briLast = briS; bri = 0;
     strip.fill(BLACK);
-    strip.show();
+    if (rlyPin < 0)
+      strip.show(); // ensure LEDs are off if no relay is used
   }
   colorUpdated(CALL_MODE_INIT); // will not send notification but will initiate transition
   if (bootPreset > 0) {
@@ -614,12 +619,6 @@ void WLED::beginStrip()
   }
 
   strip.setTransition(transitionDelayDefault);  // restore transitions
-
-  // init relay pin
-  if (rlyPin >= 0) {
-    pinMode(rlyPin, rlyOpenDrain ? OUTPUT_OPEN_DRAIN : OUTPUT);
-    digitalWrite(rlyPin, (rlyMde ? bri : !bri));
-  }
 }
 
 void WLED::initAP(bool resetAP)