diff --git a/docs/99_Journal/2026-04-16_ZNS-First-Wizard-Strategy.md b/docs/99_Journal/2026-04-16_ZNS-First-Wizard-Strategy.md
index 5ad683fe..46999eea 100644
--- a/docs/99_Journal/2026-04-16_ZNS-First-Wizard-Strategy.md
+++ b/docs/99_Journal/2026-04-16_ZNS-First-Wizard-Strategy.md
@@ -62,3 +62,12 @@ Parameter sind hiermit fixiert und umgesetzt.
   `management.endpoint.health.probes.enabled: true`).
 * **Optimierung**: Healthcheck in `dc-backend.yaml` auf `wget --no-verbose` umgestellt für bessere
   Diagnosemöglichkeiten.
+
+### Nachtrag: 2026-04-16 15:30 - Connectivity & Serialization Fixes
+
+* **Connectivity**: `ConnectivityTracker` wurde auf den korrekten Health-Pfad `/api/ping/health` umgestellt. Der Footer
+  zeigt nun korrekt den Online-Status ("Cloud synchronisiert") an.
+* **Serialization**: Behebung des Fehlers `Serializer for class 'JobIdResponse' is not found`. Die DTO-Klasse wurde im
+  Frontend in `ImportStartResponse` umbenannt (passend zum Backend) und die Sichtbarkeit auf `public` erhöht.
+* **Flexibilität**: Der ZNS-Importer unterstützt nun sowohl `.zip` als auch `.dat` Dateien (z.B. direkte
+  `VEREIN01.dat`). Die UI (`pickZnsFile`) und das ViewModel wurden entsprechend erweitert.
diff --git a/frontend/core/network/src/commonMain/kotlin/at/mocode/frontend/core/network/ConnectivityTracker.kt b/frontend/core/network/src/commonMain/kotlin/at/mocode/frontend/core/network/ConnectivityTracker.kt
index c4870400..e34db40c 100644
--- a/frontend/core/network/src/commonMain/kotlin/at/mocode/frontend/core/network/ConnectivityTracker.kt
+++ b/frontend/core/network/src/commonMain/kotlin/at/mocode/frontend/core/network/ConnectivityTracker.kt
@@ -35,7 +35,7 @@ class ConnectivityTracker : KoinComponent {
 
   private suspend fun checkConnection(): Boolean {
     return try {
-      val response = client.get(NetworkConfig.baseUrl.trimEnd('/') + "/ping")
+      val response = client.get(NetworkConfig.baseUrl.trimEnd('/') + "/api/ping/health")
       response.status.value in 200..299
     } catch (e: Exception) {
       false
diff --git a/frontend/features/zns-import-feature/src/jvmMain/kotlin/at/mocode/zns/feature/ZnsImportViewModel.kt b/frontend/features/zns-import-feature/src/jvmMain/kotlin/at/mocode/zns/feature/ZnsImportViewModel.kt
index 65683ef5..25af497b 100644
--- a/frontend/features/zns-import-feature/src/jvmMain/kotlin/at/mocode/zns/feature/ZnsImportViewModel.kt
+++ b/frontend/features/zns-import-feature/src/jvmMain/kotlin/at/mocode/zns/feature/ZnsImportViewModel.kt
@@ -24,7 +24,7 @@ import kotlin.time.Duration.Companion.milliseconds
 
 
 @Serializable
-internal data class JobIdResponse(val jobId: String)
+data class ImportStartResponse(val jobId: String)
 
 @Serializable
 internal data class JobStatusResponse(
@@ -57,8 +57,12 @@ class ZnsImportViewModel(
   override fun startImport(mode: String) {
     val filePath = state.selectedFilePath ?: return
     val file = File(filePath)
-    if (!file.exists() || !file.name.endsWith(".zip", ignoreCase = true)) {
-      state = state.copy(errorMessage = "Bitte eine gültige .zip-Datei auswählen.")
+    if (!file.exists() || !(file.name.endsWith(".zip", ignoreCase = true) || file.name.endsWith(
+        ".dat",
+        ignoreCase = true
+      ))
+    ) {
+      state = state.copy(errorMessage = "Bitte eine gültige .zip oder .dat-Datei auswählen.")
       return
     }
 
@@ -72,15 +76,17 @@ class ZnsImportViewModel(
         val response: HttpResponse = httpClient.post("${NetworkConfig.baseUrl}/api/v1/import/zns") {
           parameter("mode", mode)
           if (token != null) header(HttpHeaders.Authorization, "Bearer $token")
+          val contentType =
+            if (file.name.endsWith(".zip", ignoreCase = true)) "application/zip" else "application/octet-stream"
           setBody(MultiPartFormDataContent(formData {
             append("file", file.readBytes(), Headers.build {
               append(HttpHeaders.ContentDisposition, "filename=\"${file.name}\"")
-              append(HttpHeaders.ContentType, "application/zip")
+              append(HttpHeaders.ContentType, contentType)
             })
           }))
         }
         if (response.status == HttpStatusCode.Accepted) {
-          val body = json.decodeFromString<JobIdResponse>(response.bodyAsText())
+          val body = json.decodeFromString<ImportStartResponse>(response.bodyAsText())
           state = state.copy(isUploading = false, jobId = body.jobId, jobStatus = "AUSSTEHEND")
           startPolling(body.jobId)
         } else {
diff --git a/frontend/shells/meldestelle-desktop/src/jvmMain/kotlin/at/mocode/desktop/v2/VeranstaltungScreens.kt b/frontend/shells/meldestelle-desktop/src/jvmMain/kotlin/at/mocode/desktop/v2/VeranstaltungScreens.kt
index 10958d2e..349a0a2c 100644
--- a/frontend/shells/meldestelle-desktop/src/jvmMain/kotlin/at/mocode/desktop/v2/VeranstaltungScreens.kt
+++ b/frontend/shells/meldestelle-desktop/src/jvmMain/kotlin/at/mocode/desktop/v2/VeranstaltungScreens.kt
@@ -1587,7 +1587,11 @@ fun ZnsImportWizardSection(
     Column(modifier = Modifier.padding(16.dp), verticalArrangement = Arrangement.spacedBy(12.dp)) {
       Row(verticalAlignment = Alignment.CenterVertically, horizontalArrangement = Arrangement.spacedBy(8.dp)) {
         Icon(Icons.Default.CloudUpload, contentDescription = null, tint = MaterialTheme.colorScheme.primary)
-        Text("ZNS-Stammdaten Import (ZIP)", style = MaterialTheme.typography.titleMedium, fontWeight = FontWeight.Bold)
+        Text(
+          "ZNS-Stammdaten Import (ZIP/DAT)",
+          style = MaterialTheme.typography.titleMedium,
+          fontWeight = FontWeight.Bold
+        )
         Spacer(Modifier.weight(1f))
         if (state.isFinished || state.errorMessage != null) {
           TextButton(onClick = onReset) {
@@ -1609,14 +1613,14 @@ fun ZnsImportWizardSection(
             value = state.selectedFilePath ?: "",
             onValueChange = {},
             readOnly = true,
-            placeholder = { Text("ZNS.zip auswählen...") },
+            placeholder = { Text("ZNS-Datei auswählen (.zip, .dat)...") },
             modifier = Modifier.weight(1f),
             singleLine = true,
             textStyle = MaterialTheme.typography.bodySmall
           )
           Button(
             onClick = {
-              val path = pickZipFile()
+              val path = pickZnsFile()
               if (path != null) onFileSelect(path)
             },
             enabled = !state.isUploading
@@ -1714,10 +1718,10 @@ fun ZnsImportWizardSection(
   }
 }
 
-private fun pickZipFile(): String? {
+private fun pickZnsFile(): String? {
   val chooser = JFileChooser()
-  chooser.dialogTitle = "ZNS.zip auswählen"
-  chooser.fileFilter = FileNameExtensionFilter("ZIP-Archiv (*.zip)", "zip")
+  chooser.dialogTitle = "ZNS-Datei auswählen"
+  chooser.fileFilter = FileNameExtensionFilter("ZNS Dateien (*.zip, *.dat)", "zip", "dat")
   chooser.isAcceptAllFileFilterUsed = false
   val result = chooser.showOpenDialog(null)
   return if (result == JFileChooser.APPROVE_OPTION) chooser.selectedFile.absolutePath else null