[network] Fix last-seen channel being set to UNDEF at startup (openhab#17971)

Signed-off-by: Leo Siepel <[email protected]>

Author: lsiepel

bundles/org.openhab.binding.network/src/main/java/org/openhab/binding/network/internal/handler/NetworkHandler.java

@@ -100,11 +100,11 @@ private void refreshValue(ChannelUID channelUID) {
                 });
                 break;
             case CHANNEL_LASTSEEN:
+                // We should not set the last seen state to UNDEF, it prevents restoreOnStartup from working
+                // For reference: https://github.com/openhab/openhab-addons/issues/17404
                 Instant lastSeen = presenceDetection.getLastSeen();
                 if (lastSeen != null) {
                     updateState(CHANNEL_LASTSEEN, new DateTimeType(lastSeen));
-                } else {
-                    updateState(CHANNEL_LASTSEEN, UnDefType.UNDEF);
                 }
                 break;
             default:
@@ -144,9 +144,9 @@ public void finalDetectionResult(PresenceDetectionValue value) {
         Instant lastSeen = presenceDetection.getLastSeen();
         if (value.isReachable() && lastSeen != null) {
             updateState(CHANNEL_LASTSEEN, new DateTimeType(lastSeen));
-        } else if (!value.isReachable() && lastSeen == null) {
-            updateState(CHANNEL_LASTSEEN, UnDefType.UNDEF);
         }
+        // We should not set the last seen state to UNDEF, it prevents restoreOnStartup from working
+        // For reference: https://github.com/openhab/openhab-addons/issues/17404
 
         updateNetworkProperties();
     }