diff --git a/gns3server/handlers/api/dynamips_device_handler.py b/gns3server/handlers/api/dynamips_device_handler.py
index 95307b89..10220cec 100644
--- a/gns3server/handlers/api/dynamips_device_handler.py
+++ b/gns3server/handlers/api/dynamips_device_handler.py
@@ -181,10 +181,8 @@ class DynamipsDeviceHandler:
         dynamips_manager = Dynamips.instance()
         device = dynamips_manager.get_device(request.match_info["device_id"], project_id=request.match_info["project_id"])
         port_number = int(request.match_info["port_number"])
-        if asyncio.iscoroutinefunction(device.remove_nio):
-            yield from device.remove_nio(port_number)
-        else:
-            device.remove_nio(port_number)
+        nio = yield from device.remove_nio(port_number)
+        yield from nio.delete()
         response.set_status(204)
 
     @Route.post(
diff --git a/gns3server/handlers/api/dynamips_vm_handler.py b/gns3server/handlers/api/dynamips_vm_handler.py
index c125bbb2..8d96f98b 100644
--- a/gns3server/handlers/api/dynamips_vm_handler.py
+++ b/gns3server/handlers/api/dynamips_vm_handler.py
@@ -290,7 +290,8 @@ class DynamipsVMHandler:
         vm = dynamips_manager.get_vm(request.match_info["vm_id"], project_id=request.match_info["project_id"])
         slot_number = int(request.match_info["adapter_number"])
         port_number = int(request.match_info["port_number"])
-        yield from vm.slot_remove_nio_binding(slot_number, port_number)
+        nio = yield from vm.slot_remove_nio_binding(slot_number, port_number)
+        yield from nio.delete()
         response.set_status(204)
 
     @Route.post(
diff --git a/gns3server/modules/dynamips/nodes/atm_switch.py b/gns3server/modules/dynamips/nodes/atm_switch.py
index 4064ad07..141293af 100644
--- a/gns3server/modules/dynamips/nodes/atm_switch.py
+++ b/gns3server/modules/dynamips/nodes/atm_switch.py
@@ -150,6 +150,7 @@ class ATMSwitch(Device):
 
         self._nios[port_number] = nio
 
+    @asyncio.coroutine
     def remove_nio(self, port_number):
         """
         Removes the specified NIO as member of this ATM switch.
@@ -160,6 +161,23 @@ class ATMSwitch(Device):
         if port_number not in self._nios:
             raise DynamipsError("Port {} is not allocated".format(port_number))
 
+        # remove VCs mapped with the port
+        for source, destination in self._mappings.copy().items():
+            if len(source) == 3 and len(destination) == 3:
+                # remove the virtual channels mapped with this port/nio
+                source_port, source_vpi, source_vci = source
+                destination_port, destination_vpi, destination_vci = destination
+                if port_number == source_port:
+                    yield from self.unmap_pvc(source_port, source_vpi, source_vci, destination_port, destination_vpi, destination_vci)
+                    yield from self.unmap_pvc(destination_port, destination_vpi, destination_vci, source_port, source_vpi, source_vci)
+            else:
+                # remove the virtual paths mapped with this port/nio
+                source_port, source_vpi = source
+                destination_port, destination_vpi = destination
+                if port_number == source_port:
+                    yield from self.unmap_vp(source_port, source_vpi, destination_port, destination_vpi)
+                    yield from self.unmap_vp(destination_port, destination_vpi, source_port, source_vpi)
+
         nio = self._nios[port_number]
         if isinstance(nio, NIOUDP):
             self.manager.port_manager.release_udp_port(nio.lport, self._project)
diff --git a/gns3server/modules/dynamips/nodes/frame_relay_switch.py b/gns3server/modules/dynamips/nodes/frame_relay_switch.py
index a4bf56e6..c1f06c84 100644
--- a/gns3server/modules/dynamips/nodes/frame_relay_switch.py
+++ b/gns3server/modules/dynamips/nodes/frame_relay_switch.py
@@ -149,6 +149,7 @@ class FrameRelaySwitch(Device):
 
         self._nios[port_number] = nio
 
+    @asyncio.coroutine
     def remove_nio(self, port_number):
         """
         Removes the specified NIO as member of this Frame Relay switch.
@@ -161,6 +162,14 @@ class FrameRelaySwitch(Device):
         if port_number not in self._nios:
             raise DynamipsError("Port {} is not allocated".format(port_number))
 
+        # remove VCs mapped with the port
+        for source, destination in self._mappings.copy().items():
+            source_port, source_dlci = source
+            destination_port, destination_dlci = destination
+            if port_number == source_port:
+                yield from self.unmap_vc(source_port, source_dlci, destination_port, destination_dlci)
+                yield from self.unmap_vc(destination_port, destination_dlci, source_port, source_dlci)
+
         nio = self._nios[port_number]
         if isinstance(nio, NIOUDP):
             self.manager.port_manager.release_udp_port(nio.lport, self._project)
diff --git a/gns3server/modules/dynamips/nodes/router.py b/gns3server/modules/dynamips/nodes/router.py
index 568a11f6..7182eb50 100644
--- a/gns3server/modules/dynamips/nodes/router.py
+++ b/gns3server/modules/dynamips/nodes/router.py
@@ -172,14 +172,6 @@ class Router(BaseVM):
 
         return router_info
 
-    @classmethod
-    def reset(cls):
-        """
-        Resets the instance count and the allocated instances list.
-        """
-
-        cls._dynamips_ids.clear()
-
     @property
     def dynamips_id(self):
         """