diff --git a/src/libnm-core-impl/nm-setting.c b/src/libnm-core-impl/nm-setting.c
index ce40c61d38..3f32e181d8 100644
--- a/src/libnm-core-impl/nm-setting.c
+++ b/src/libnm-core-impl/nm-setting.c
@@ -543,7 +543,8 @@ _nm_setting_property_to_dbus_fcn_get_boolean(const NMSettInfoSetting *
     gboolean                  val;
 
     val = !!property_info->to_dbus_data.get_boolean(setting);
-    if (val == NM_G_PARAM_SPEC_GET_DEFAULT_BOOLEAN(property_info->param_spec))
+    if (!property_info->to_dbus_data.including_default
+        && val == NM_G_PARAM_SPEC_GET_DEFAULT_BOOLEAN(property_info->param_spec))
         return NULL;
     return g_variant_ref(nm_g_variant_singleton_b(val));
 }
@@ -559,7 +560,13 @@ _nm_setting_property_to_dbus_fcn_get_string(const NMSettInfoSetting *
     const NMSettInfoProperty *property_info = &sett_info->property_infos[property_idx];
     const char *              val;
 
+    /* For string properties that are implemented via this function, the default is always NULL.
+     * In general, having strings default to NULL is most advisable.
+     *
+     * Setting "including_default" for a string makes no sense because a
+     * GVariant of type "s" cannot express NULL. */
     nm_assert(!NM_G_PARAM_SPEC_GET_DEFAULT_STRING(property_info->param_spec));
+    nm_assert(!property_info->to_dbus_data.including_default);
 
     val = property_info->to_dbus_data.get_string(setting);
     if (!val)
@@ -593,7 +600,8 @@ _nm_setting_property_to_dbus_fcn_gprop(const NMSettInfoSetting *               s
 
     g_object_get_property(G_OBJECT(setting), property->param_spec->name, &prop_value);
 
-    if (g_param_value_defaults(property->param_spec, &prop_value))
+    if (!property->to_dbus_data.including_default
+        && g_param_value_defaults(property->param_spec, &prop_value))
         return NULL;
 
     switch (property->property_type->typdata_to_dbus.gprop_type) {
diff --git a/src/libnm-core-impl/tests/test-setting.c b/src/libnm-core-impl/tests/test-setting.c
index 77edf4afa4..066cdb24d9 100644
--- a/src/libnm-core-impl/tests/test-setting.c
+++ b/src/libnm-core-impl/tests/test-setting.c
@@ -4358,6 +4358,7 @@ test_setting_metadata(void)
             const NMSettInfoProperty *sip = &sis->property_infos[prop_idx];
             GArray *                  property_types_data;
             guint                     prop_idx_val;
+            gboolean                  can_set_including_default = FALSE;
 
             g_assert(sip->name);
 
@@ -4402,11 +4403,13 @@ check_done:;
                 if (sip->property_type->typdata_to_dbus.gprop_type
                     != NM_SETTING_PROPERTY_TO_DBUS_FCN_GPROP_TYPE_DEFAULT)
                     g_assert(!sip->to_dbus_data.gprop_to_dbus_fcn);
+                can_set_including_default = TRUE;
             } else if (sip->property_type->to_dbus_fcn
                        == _nm_setting_property_to_dbus_fcn_get_boolean) {
                 g_assert(sip->param_spec);
                 g_assert(sip->param_spec->value_type == G_TYPE_BOOLEAN);
                 g_assert(sip->to_dbus_data.get_boolean);
+                can_set_including_default = TRUE;
             } else if (sip->property_type->to_dbus_fcn
                        == _nm_setting_property_to_dbus_fcn_get_string) {
                 g_assert(sip->param_spec);
@@ -4414,6 +4417,9 @@ check_done:;
                 g_assert(sip->to_dbus_data.get_string);
             }
 
+            if (!can_set_including_default)
+                g_assert(!sip->to_dbus_data.including_default);
+
             g_assert(!sip->property_type->from_dbus_fcn
                      || !sip->property_type->gprop_from_dbus_fcn);
 
diff --git a/src/libnm-core-intern/nm-core-internal.h b/src/libnm-core-intern/nm-core-internal.h
index c4e420f0d8..2ef2520956 100644
--- a/src/libnm-core-intern/nm-core-internal.h
+++ b/src/libnm-core-intern/nm-core-internal.h
@@ -714,6 +714,12 @@ struct _NMSettInfoProperty {
             gboolean (*get_boolean)(NMSetting *);
             const char *(*get_string)(NMSetting *);
         };
+
+        /* Usually, properties that are set to the default value for the GParamSpec
+         * are not serialized to GVariant (and NULL is returned by to_dbus_data().
+         * Set this flag to force always converting the property even if the value
+         * is the default. */
+        bool including_default : 1;
     } to_dbus_data;
 };