diff --git a/src/helpers/radiolib/CustomLR1110.h b/src/helpers/radiolib/CustomLR1110.h
index 4061c6b1a6..87a7005f58 100644
--- a/src/helpers/radiolib/CustomLR1110.h
+++ b/src/helpers/radiolib/CustomLR1110.h
@@ -4,6 +4,10 @@
 #include "MeshCore.h"
 
 class CustomLR1110 : public LR1110 {
+  uint32_t _preambleMillis = 66;
+  uint32_t _maxPayloadMillis = 3934;
+  uint32_t _activityAt = 0;
+  bool _headerSeen = false;
   bool _rx_boosted = false;
 
   public:
@@ -32,9 +36,46 @@ class CustomLR1110 : public LR1110 {
     bool getRxBoostedGainMode() const { return _rx_boosted; }
 
     bool isReceiving() {
-      uint16_t irq = getIrqStatus();
-      bool detected = ((irq & RADIOLIB_LR11X0_IRQ_SYNC_WORD_HEADER_VALID) || (irq & RADIOLIB_LR11X0_IRQ_PREAMBLE_DETECTED));
-      return detected;
+      uint32_t irq = getIrqStatus();
+      bool preamble = irq & RADIOLIB_LR11X0_IRQ_PREAMBLE_DETECTED;      // bit 4
+      bool header   = irq & RADIOLIB_LR11X0_IRQ_SYNC_WORD_HEADER_VALID; // bit 5
+      bool hdrErr   = irq & RADIOLIB_LR11X0_IRQ_HEADER_ERR;             // bit 6
+      uint32_t now  = millis();
+      if (hdrErr) {
+        clearIrqState(RADIOLIB_LR11X0_IRQ_PREAMBLE_DETECTED | RADIOLIB_LR11X0_IRQ_SYNC_WORD_HEADER_VALID | RADIOLIB_LR11X0_IRQ_HEADER_ERR);
+        _activityAt = 0;
+        _headerSeen = false;
+        return false;
+      }
+      if (header) {
+        if (!_headerSeen) { _headerSeen = true; _activityAt = now; };
+        if (now - _activityAt > _maxPayloadMillis) {
+          MESH_DEBUG_PRINTLN("Clearing header IRQ after %ums", _maxPayloadMillis);
+          clearIrqState(RADIOLIB_LR11X0_IRQ_PREAMBLE_DETECTED | RADIOLIB_LR11X0_IRQ_SYNC_WORD_HEADER_VALID | RADIOLIB_LR11X0_IRQ_HEADER_ERR);
+          _activityAt = 0; _headerSeen = false;
+          return false;
+        }
+        return true;
+      }
+      if (preamble) {
+        if (_activityAt == 0) _activityAt = now;
+        if (now - _activityAt > _preambleMillis) {
+          clearIrqState(RADIOLIB_LR11X0_IRQ_PREAMBLE_DETECTED);
+          _activityAt = 0;
+          MESH_DEBUG_PRINTLN("Clearing preamble IRQ after %ums", _preambleMillis);
+
+          return false;
+        }
+        return true;
+      }
+      _activityAt = 0; _headerSeen = false;
+      return false;
+    }
+
+    void setMaxPacketMillis(PacketMillis maxPacketMillis) {
+      MESH_DEBUG_PRINTLN("Setting _preambleMillis=%u, _maxPacketMillis=%u", maxPacketMillis.preambleMillis, maxPacketMillis.payloadMillis);
+      _preambleMillis = maxPacketMillis.preambleMillis;
+      _maxPayloadMillis = maxPacketMillis.payloadMillis;
     }
 
     uint8_t getSpreadingFactor() const { return spreadingFactor; }
diff --git a/src/helpers/radiolib/CustomLR1110Wrapper.h b/src/helpers/radiolib/CustomLR1110Wrapper.h
index c6b1acb472..981faf092a 100644
--- a/src/helpers/radiolib/CustomLR1110Wrapper.h
+++ b/src/helpers/radiolib/CustomLR1110Wrapper.h
@@ -14,6 +14,8 @@ class CustomLR1110Wrapper : public RadioLibWrapper {
     ((CustomLR1110 *)_radio)->setBandwidth(bw);
     ((CustomLR1110 *)_radio)->setCodingRate(cr);
     updatePreamble(sf);
+    ((CustomLR1110 *)_radio)->setMaxPacketMillis(calcMaxPacketMillis(sf, bw, cr, preambleLengthForSF(sf)));
+
   }
 
   void doResetAGC() override { lr11x0ResetAGC((LR11x0 *)_radio, ((CustomLR1110 *)_radio)->getFreqMHz()); }
diff --git a/src/helpers/radiolib/CustomSX1262.h b/src/helpers/radiolib/CustomSX1262.h
index ca62fc26af..18932488a3 100644
--- a/src/helpers/radiolib/CustomSX1262.h
+++ b/src/helpers/radiolib/CustomSX1262.h
@@ -3,10 +3,12 @@
 #include <RadioLib.h>
 #include "MeshCore.h"
 
-#define SX126X_IRQ_HEADER_VALID                0b0000010000  //  4     4     valid LoRa header received
-#define SX126X_IRQ_PREAMBLE_DETECTED           0x04
-
 class CustomSX1262 : public SX1262 {
+  uint32_t _preambleMillis = 66;
+  uint32_t _maxPayloadMillis = 3934;
+  uint32_t _activityAt = 0;
+  bool _headerSeen = false;
+
   public:
     CustomSX1262(Module *mod) : SX1262(mod) { }
 
@@ -99,9 +101,46 @@ class CustomSX1262 : public SX1262 {
     }
 
     bool isReceiving() {
-      uint16_t irq = getIrqFlags();
-      bool detected = (irq & SX126X_IRQ_HEADER_VALID) || (irq & SX126X_IRQ_PREAMBLE_DETECTED);
-      return detected;
+      uint32_t irq = getIrqFlags();
+      bool preamble = irq & RADIOLIB_SX126X_IRQ_PREAMBLE_DETECTED; // bit 2
+      bool header   = irq & RADIOLIB_SX126X_IRQ_HEADER_VALID;      // bit 4
+      bool hdrErr   = irq & RADIOLIB_SX126X_IRQ_HEADER_ERR;        // bit 5
+      uint32_t now  = millis();
+      if (hdrErr) {
+        clearIrqFlags(RADIOLIB_SX126X_IRQ_PREAMBLE_DETECTED | RADIOLIB_SX126X_IRQ_HEADER_VALID | RADIOLIB_SX126X_IRQ_HEADER_ERR | RADIOLIB_SX126X_IRQ_SYNC_WORD_VALID);
+        _activityAt = 0;
+        _headerSeen = false;
+        return false;
+      }
+      if (header) {
+        if (!_headerSeen) { _headerSeen = true; _activityAt = now; };
+        if (now - _activityAt > _maxPayloadMillis) {
+          MESH_DEBUG_PRINTLN("Clearing header IRQ after %ums", _maxPayloadMillis);
+          clearIrqFlags(RADIOLIB_SX126X_IRQ_PREAMBLE_DETECTED | RADIOLIB_SX126X_IRQ_HEADER_VALID | RADIOLIB_SX126X_IRQ_HEADER_ERR | RADIOLIB_SX126X_IRQ_SYNC_WORD_VALID);
+          _activityAt = 0; _headerSeen = false;
+          return false;
+        }
+        return true;
+      }
+      if (preamble) {
+        if (_activityAt == 0) _activityAt = now;
+        if (now - _activityAt > _preambleMillis) {
+          clearIrqStatus(RADIOLIB_IRQ_PREAMBLE_DETECTED);
+          _activityAt = 0;
+          MESH_DEBUG_PRINTLN("Clearing preamble IRQ after %ums", _preambleMillis);
+
+          return false;
+        }
+        return true;
+      }
+      _activityAt = 0; _headerSeen = false;
+      return false;
+    }
+
+    void setMaxPacketMillis(PacketMillis maxPacketMillis) {
+      MESH_DEBUG_PRINTLN("Setting _preambleMillis=%u, _maxPacketMillis=%u", maxPacketMillis.preambleMillis, maxPacketMillis.payloadMillis);
+      _preambleMillis = maxPacketMillis.preambleMillis;
+      _maxPayloadMillis = maxPacketMillis.payloadMillis;
     }
 
     bool getRxBoostedGainMode() {
diff --git a/src/helpers/radiolib/CustomSX1262Wrapper.h b/src/helpers/radiolib/CustomSX1262Wrapper.h
index 1d103f5790..45af4cb4bb 100644
--- a/src/helpers/radiolib/CustomSX1262Wrapper.h
+++ b/src/helpers/radiolib/CustomSX1262Wrapper.h
@@ -18,6 +18,7 @@ class CustomSX1262Wrapper : public RadioLibWrapper {
     ((CustomSX1262 *)_radio)->setBandwidth(bw);
     ((CustomSX1262 *)_radio)->setCodingRate(cr);
     updatePreamble(sf);
+    ((CustomSX1262 *)_radio)->setMaxPacketMillis(calcMaxPacketMillis(sf, bw, cr, preambleLengthForSF(sf)));
   }
 
   bool isReceivingPacket() override { 
diff --git a/src/helpers/radiolib/RadioLibWrappers.cpp b/src/helpers/radiolib/RadioLibWrappers.cpp
index 5e72336c05..7146e47b6a 100644
--- a/src/helpers/radiolib/RadioLibWrappers.cpp
+++ b/src/helpers/radiolib/RadioLibWrappers.cpp
@@ -228,3 +228,21 @@ float RadioLibWrapper::packetScoreInt(float snr, int sf, int packet_len) {
 
   return max(0.0, min(1.0, success_rate_based_on_snr * collision_penalty));
 }
+
+PacketMillis RadioLibWrapper::calcMaxPacketMillis(uint8_t sf, float bw, uint8_t cr, uint8_t preambleSymbols) {
+  // based on RadioLib's calculateTimeOnAir()
+  uint32_t tsym_us = ((uint32_t)10000 << sf) / (bw * 10);
+  uint32_t sfCoeff1_x4 = (sf == 5 || sf == 6) ? 25 : 17; // 6.25 : 4.25, semtech magic numbers to account for sync word + sfd
+
+  // preamble + syncword + sfd + header
+  uint32_t preamble_us = (((preambleSymbols + 8) * 4 + sfCoeff1_x4) * tsym_us) / 4;
+  
+  // airtime for max packet at current radio settings
+  uint32_t total_us   = _radio->getTimeOnAir(MAX_TRANS_UNIT);
+  // airtime for payload only (no preamble, header or SOF)
+  uint32_t payload_us = total_us > preamble_us ? total_us - preamble_us : 4000 - preamble_us; // fallback to 4 secs at worst case
+  // rescale payload_us for max possible CR
+  if (cr >= 5 && cr < 8) { payload_us = (payload_us * 8) / cr; }
+
+  return PacketMillis {(preamble_us + 999) / 1000, (payload_us + 999) / 1000};
+}
\ No newline at end of file
diff --git a/src/helpers/radiolib/RadioLibWrappers.h b/src/helpers/radiolib/RadioLibWrappers.h
index 3091832f11..e7fef91042 100644
--- a/src/helpers/radiolib/RadioLibWrappers.h
+++ b/src/helpers/radiolib/RadioLibWrappers.h
@@ -3,6 +3,11 @@
 #include <Mesh.h>
 #include <RadioLib.h>
 
+struct PacketMillis {
+  uint32_t preambleMillis;  // preamble-detect -> header-valid deadline
+  uint32_t payloadMillis;   // header-valid   -> rx-done deadline
+};
+
 class RadioLibWrapper : public mesh::Radio {
 protected:
   PhysicalLayer* _radio;
@@ -47,6 +52,7 @@ class RadioLibWrapper : public mesh::Radio {
   virtual uint8_t getSpreadingFactor() const { return LORA_SF; }
   static uint16_t preambleLengthForSF(uint8_t sf) { return sf <= 8 ? 32 : 16; }
   void updatePreamble(uint8_t sf) { _preamble_sf = sf; _radio->setPreambleLength(preambleLengthForSF(sf)); }
+  PacketMillis calcMaxPacketMillis(uint8_t sf, float bw, uint8_t cr, uint8_t preambleSymbols);
   virtual int16_t performChannelScan();
 
   int getNoiseFloor() const override { return _noise_floor; }