diff --git a/src/core/devices/nm-device.c b/src/core/devices/nm-device.c
index 497108b1c..6723d1415 100644
--- a/src/core/devices/nm-device.c
+++ b/src/core/devices/nm-device.c
@@ -3043,6 +3043,7 @@ nm_device_sys_iface_state_set(NMDevice *self, NMDeviceSysIfaceState sys_iface_st
               nm_device_sys_iface_state_to_string(sys_iface_state));
         priv->sys_iface_state_ = sys_iface_state;
         _dev_l3_cfg_commit_type_reset(self);
+        nm_device_l3cfg_commit(self, NM_L3_CFG_COMMIT_TYPE_AUTO, FALSE);
     }
 
     /* this function only sets a flag, no immediate actions are initiated.
@@ -11326,10 +11327,8 @@ _commit_mtu(NMDevice *self)
     if (ifindex <= 0)
         return;
 
-    if (!nm_device_get_applied_connection(self)
-        || nm_device_sys_iface_state_is_external_or_assume(self)) {
-        /* we don't tamper with the MTU of disconnected and
-         * external/assumed devices. */
+    if (!nm_device_get_applied_connection(self) || nm_device_sys_iface_state_is_external(self)) {
+        /* we don't tamper with the MTU of disconnected and external devices. */
         return;
     }