diff --git a/src/customwidgets/deviceconfigtab.cpp b/src/customwidgets/deviceconfigtab.cpp
index bd0e0e90..11ce6418 100644
--- a/src/customwidgets/deviceconfigtab.cpp
+++ b/src/customwidgets/deviceconfigtab.cpp
@@ -21,7 +21,8 @@ DeviceConfigTab::DeviceConfigTab(SettingsModel* pSettingsModel,
       _pNameEdit(new QLineEdit(this)),
       _pAdapterCombo(new QComboBox(this)),
       _pSchemaForm(nullptr),
-      _pSettingsModel(pSettingsModel)
+      _pSettingsModel(pSettingsModel),
+      _deviceId(deviceValues.value("id").toInt(-1))
 {
     _pLayout = new QVBoxLayout(this);
     setLayout(_pLayout);
@@ -84,6 +85,17 @@ void DeviceConfigTab::onAdapterChanged(int index)
     {
         defaultValues = defaultDevices.first().toObject();
     }
+
+    // Preserve the existing device id so that switching adapters does not overwrite
+    // the unique id assigned when the tab was created. Fall back to _deviceId when
+    // the id field is hidden in the schema form and not returned by values().
+    int currentId = _pSchemaForm ? _pSchemaForm->values().value("id").toInt(-1) : -1;
+    if (currentId < 0)
+    {
+        currentId = _deviceId;
+    }
+    defaultValues["id"] = currentId;
+
     rebuildSchemaForm(newAdapterId, defaultValues);
 }
 
diff --git a/src/customwidgets/deviceconfigtab.h b/src/customwidgets/deviceconfigtab.h
index d402b868..097c43e9 100644
--- a/src/customwidgets/deviceconfigtab.h
+++ b/src/customwidgets/deviceconfigtab.h
@@ -57,6 +57,7 @@ private slots:
     QComboBox* _pAdapterCombo;
     SchemaFormWidget* _pSchemaForm;
     SettingsModel* _pSettingsModel;
+    int _deviceId;
 };
 
 #endif // DEVICECONFIGTAB_H
diff --git a/src/dialogs/adapterdevicesettings.cpp b/src/dialogs/adapterdevicesettings.cpp
index 1e3bd97e..cda47875 100644
--- a/src/dialogs/adapterdevicesettings.cpp
+++ b/src/dialogs/adapterdevicesettings.cpp
@@ -63,6 +63,12 @@ AdapterDeviceSettings::AdapterDeviceSettings(SettingsModel* pSettingsModel, QWid
     }
 }
 
+/*! \brief Add a new device tab with a unique, auto-incremented device ID.
+ *
+ * Creates a SettingsModel device via addNewDevice() to obtain a unique ID,
+ * sets its adapter, then opens a new DeviceConfigTab pre-populated with
+ * the adapter's default values and the assigned ID.
+ */
 void AdapterDeviceSettings::handleAddTab()
 {
     QString defaultAdapterId;
@@ -90,6 +96,10 @@ void AdapterDeviceSettings::handleAddTab()
         defaultValues = defaultDevices.first().toObject();
     }
 
+    deviceId_t newId = _pSettingsModel->addNewDevice();
+    _pSettingsModel->deviceSettings(newId)->setAdapterId(defaultAdapterId);
+    defaultValues["id"] = static_cast<int>(newId);
+
     int tabIndex = _pDeviceTabs->count() + 1;
     auto* tab = new DeviceConfigTab(_pSettingsModel, defaultAdapterId, defaultValues, _pDeviceTabs);
     _pDeviceTabs->addNewTab(constructTabName(defaultValues, tabIndex), tab);
diff --git a/tests/dialogs/tst_adapterdevicesettings.cpp b/tests/dialogs/tst_adapterdevicesettings.cpp
index 4fcd842d..40ab9366 100644
--- a/tests/dialogs/tst_adapterdevicesettings.cpp
+++ b/tests/dialogs/tst_adapterdevicesettings.cpp
@@ -5,6 +5,7 @@
 #include "dialogs/adapterdevicesettings.h"
 #include "models/settingsmodel.h"
 
+#include <QComboBox>
 #include <QJsonArray>
 #include <QJsonObject>
 #include <QLabel>
@@ -229,7 +230,80 @@ void TestAdapterDeviceSettings::addTabUsesDeviceDefaults()
 
     auto* spin = tab->findChild<QSpinBox*>();
     QVERIFY(spin != nullptr);
-    QCOMPARE(spin->value(), 5);
+    // The adapter default id (5) must be overridden with a unique SettingsModel id.
+    const int assignedId = spin->value();
+    QVERIFY(assignedId != 5);
+    QVERIFY(model.hasDevice(static_cast<deviceId_t>(assignedId)));
+    QCOMPARE(model.deviceSettings(static_cast<deviceId_t>(assignedId))->adapterId(), QStringLiteral("adapterA"));
+}
+
+void TestAdapterDeviceSettings::addTabIncrementsDeviceId()
+{
+    SettingsModel model;
+    setupAdapter(model, "adapterA", QJsonArray());
+
+    AdapterDeviceSettings w(&model);
+
+    auto* tabs = w.findChild<AddableTabWidget*>();
+    QVERIFY(tabs != nullptr);
+    QCOMPARE(tabs->count(), 0);
+
+    emit tabs->addTabRequested();
+    emit tabs->addTabRequested();
+
+    QCOMPARE(tabs->count(), 2);
+
+    auto* tab0 = qobject_cast<DeviceConfigTab*>(tabs->tabContent(0));
+    auto* tab1 = qobject_cast<DeviceConfigTab*>(tabs->tabContent(1));
+    QVERIFY(tab0 != nullptr);
+    QVERIFY(tab1 != nullptr);
+
+    const int id0 = tab0->values().value("id").toInt(-1);
+    const int id1 = tab1->values().value("id").toInt(-1);
+
+    QVERIFY(id0 >= 1);
+    QVERIFY(id1 > id0);
+
+    // Both ids must be present in the SettingsModel and linked to the adapter.
+    QVERIFY(model.hasDevice(static_cast<deviceId_t>(id0)));
+    QVERIFY(model.hasDevice(static_cast<deviceId_t>(id1)));
+    QCOMPARE(model.deviceSettings(static_cast<deviceId_t>(id0))->adapterId(), QStringLiteral("adapterA"));
+    QCOMPARE(model.deviceSettings(static_cast<deviceId_t>(id1))->adapterId(), QStringLiteral("adapterA"));
+}
+
+void TestAdapterDeviceSettings::deviceIdPreservedWhenAdapterChanged()
+{
+    SettingsModel model;
+    setupAdapter(model, "adapterA", QJsonArray());
+    setupAdapter(model, "adapterB", QJsonArray());
+
+    AdapterDeviceSettings w(&model);
+
+    auto* tabs = w.findChild<AddableTabWidget*>();
+    QVERIFY(tabs != nullptr);
+
+    emit tabs->addTabRequested();
+
+    QCOMPARE(tabs->count(), 1);
+    auto* tab = qobject_cast<DeviceConfigTab*>(tabs->tabContent(0));
+    QVERIFY(tab != nullptr);
+
+    const int originalId = tab->values().value("id").toInt(-1);
+    QVERIFY(originalId >= 1);
+
+    // Trigger DeviceConfigTab::onAdapterChanged by switching the adapter combo
+    auto* adapterCombo = tab->findChild<QComboBox*>();
+    QVERIFY(adapterCombo != nullptr);
+    int adapterBIdx = adapterCombo->findData(QStringLiteral("adapterB"));
+    QVERIFY(adapterBIdx >= 0);
+    adapterCombo->setCurrentIndex(adapterBIdx);
+
+    // The device ID must be preserved across the adapter switch
+    QCOMPARE(tab->values().value("id").toInt(-1), originalId);
+    // The device must still exist in the model
+    QVERIFY(model.hasDevice(static_cast<deviceId_t>(originalId)));
+    // The tab must now report the new adapter
+    QCOMPARE(tab->adapterId(), QStringLiteral("adapterB"));
 }
 
 QTEST_MAIN(TestAdapterDeviceSettings)
diff --git a/tests/dialogs/tst_adapterdevicesettings.h b/tests/dialogs/tst_adapterdevicesettings.h
index 5dd19608..e8c91900 100644
--- a/tests/dialogs/tst_adapterdevicesettings.h
+++ b/tests/dialogs/tst_adapterdevicesettings.h
@@ -18,6 +18,8 @@ private slots:
     void acceptValuesSavesToAdapterConfig();
     void acceptValuesSavesDeviceNameToModel();
     void addTabUsesDeviceDefaults();
+    void addTabIncrementsDeviceId();
+    void deviceIdPreservedWhenAdapterChanged();
 
 private:
     //! Populate \a model with an adapter that has a minimal device schema and