diff --git a/containers/synchronizer/Makefile b/containers/synchronizer/Makefile
index 733e7b8..352616a 100644
--- a/containers/synchronizer/Makefile
+++ b/containers/synchronizer/Makefile
@@ -1,6 +1,6 @@
 IMAGE_NAME:=xosproject/xos-synchronizer-openstack
 CONTAINER_NAME:=xos-synchronizer
-NO_DOCKER_CACHE?=true
+NO_DOCKER_CACHE?=false
 
 .PHONY: build
 build: ; sudo docker build --no-cache=${NO_DOCKER_CACHE} --rm -t ${IMAGE_NAME} .
diff --git a/xos/configurations/devel/Makefile b/xos/configurations/devel/Makefile
index 1e650f3..402309b 100644
--- a/xos/configurations/devel/Makefile
+++ b/xos/configurations/devel/Makefile
@@ -46,3 +46,8 @@
 
 rebuild_synchronizer:
 	make -C ../../../containers/synchronizer
+
+cleanup_docker: rm
+	sudo docker rm -v $(docker ps -a -q -f status=exited) || true
+	sudo docker rmi $(docker images -f "dangling=true" -q) || true
+	sudo docker run -v /var/run/docker.sock:/var/run/docker.sock -v /var/lib/docker:/var/lib/docker --rm martin/docker-cleanup-volumes || true
diff --git a/xos/configurations/frontend/Makefile b/xos/configurations/frontend/Makefile
index 5c0ce0e..3f1a6ab 100644
--- a/xos/configurations/frontend/Makefile
+++ b/xos/configurations/frontend/Makefile
@@ -29,3 +29,8 @@
 	sudo docker-compose run xos python /opt/xos/tosca/run.py padmin@vicci.org /opt/xos/configurations/frontend/mocks/cord.yaml
 	sudo docker exec frontend_xos_1 cp /opt/xos/configurations/cord/xos_cord_config /opt/xos/xos_configuration/
 	sudo docker exec frontend_xos_1 touch /opt/xos/xos/settings.py
+
+cleanup_docker: rm
+	sudo docker rm -v $(docker ps -a -q -f status=exited) || true
+	sudo docker rmi $(docker images -f "dangling=true" -q) || true
+	sudo docker run -v /var/run/docker.sock:/var/run/docker.sock -v /var/lib/docker:/var/lib/docker --rm martin/docker-cleanup-volumes || true
diff --git a/xos/services/vpn/admin.py b/xos/services/vpn/admin.py
index bad75e3..8adb28f 100644
--- a/xos/services/vpn/admin.py
+++ b/xos/services/vpn/admin.py
@@ -77,7 +77,8 @@
             self.fields[
                 'clients_can_see_each_other'].initial = self.instance.clients_can_see_each_other
             self.fields['is_persistent'].initial = self.instance.is_persistent
-            self.fields['failover_servers'].initial = serializers.deserialize('json', self.instance.failover_servers)
+            if (self.instance.failover_servers):
+                self.fields['failover_servers'].initial = [model.pk for model in list(serializers.deserialize('json', self.instance.failover_servers))]
 
         if (not self.instance) or (not self.instance.pk):
             self.fields['creator'].initial = get_request().user