diff --git a/nRFMeshProvision/Layers/Access Layer/AccessLayer.swift b/nRFMeshProvision/Layers/Access Layer/AccessLayer.swift
index 33ef58d09..d8a105ad3 100644
--- a/nRFMeshProvision/Layers/Access Layer/AccessLayer.swift	
+++ b/nRFMeshProvision/Layers/Access Layer/AccessLayer.swift	
@@ -238,8 +238,7 @@ internal class AccessLayer {
         
         // Set timers for the acknowledged messages.
         // Acknowledged messages sent to a Group address won't await a Status.
-        if message is AcknowledgedMeshMessage,
-           destination.address.isUnicast {
+        if message.isAcknowledged, destination.address.isUnicast {
             createReliableContext(for: pdu, sentFrom: element, withTtl: initialTtl, using: keySet)
         }
         
diff --git a/nRFMeshProvision/Layers/Lower Transport Layer/LowerTransportLayer.swift b/nRFMeshProvision/Layers/Lower Transport Layer/LowerTransportLayer.swift
index 0262559c6..3808b4bc4 100644
--- a/nRFMeshProvision/Layers/Lower Transport Layer/LowerTransportLayer.swift	
+++ b/nRFMeshProvision/Layers/Lower Transport Layer/LowerTransportLayer.swift	
@@ -254,7 +254,12 @@ internal class LowerTransportLayer {
                                        from: localElement, to: pdu.destination)
         } catch {
             logger?.w(.lowerTransport, error)
-            if !pdu.message!.isAcknowledged {
+            if pdu.message!.isAcknowledged && pdu.destination.address.isUnicast {
+                // Acknowledged messages sent to a Unicast Address will be retransmitted
+                // by the Access Layer. Nothing to be done here.
+                // See: https://github.com/NordicSemiconductor/IOS-nRF-Mesh-Library/issues/599
+            } else {
+                // 
                 networkManager.notifyAbout(error: error, duringSendingMessage: pdu.message!,
                                            from: localElement, to: pdu.destination)
             }
diff --git a/nRFMeshProvision/Layers/NetworkManager.swift b/nRFMeshProvision/Layers/NetworkManager.swift
index 5b699cb56..6f5a3324d 100644
--- a/nRFMeshProvision/Layers/NetworkManager.swift
+++ b/nRFMeshProvision/Layers/NetworkManager.swift
@@ -158,7 +158,7 @@ internal class NetworkManager {
         // If retransmission was configured, start the timer that will retransmit.
         // There is no need to retransmit acknowledged messages, as they have their
         // own retransmission mechanism.
-        if !(message is AcknowledgedMeshMessage) {
+        if !message.isAcknowledged {
             var count = publish.retransmit.count
             if count > 0 {
                 let interval: TimeInterval = Double(publish.retransmit.interval) / 1000