Hello I use openstack Ussuri in Ubuntu 18 and one controller node and one compute node with two interface, management and Provider that connected to internet i install keystone, glance, placement, nova, neutron on self service option *what i can * i can create provider network and self service network and router between them i can ping router i can launch instance on self service network and it has access to internet and everything looks fine *what i can NOT* I can't launch instances on the provider network. When I launch an instance on the provider network, the provider interface of the compute node will be corrupted and not respond and the instance will not be created. error in instance : *Message *Build of instance 2a86a84b-50fc-415c-a15c-cb87398f37ea aborted: Failed to allocate the network(s), not rescheduling. *Code *500 *Details *Traceback (most recent call last): File "/usr/lib/python3/dist-packages/nova/virt/libvirt/driver.py", line 6529, in _create_domain_and_network post_xml_callback=post_xml_callback) File "/usr/lib/python3.6/contextlib.py", line 88, in __exit__ next(self.gen) File "/usr/lib/python3/dist-packages/nova/compute/manager.py", line 513, in wait_for_instance_event actual_event = event.wait() File "/usr/lib/python3/dist-packages/eventlet/event.py", line 125, in wait result = hub.switch() File "/usr/lib/python3/dist-packages/eventlet/hubs/hub.py", line 298, in switch return self.greenlet.switch() eventlet.timeout.Timeout: 300 seconds During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/usr/lib/python3/dist-packages/nova/compute/manager.py", line 2378, in _build_and_run_instance accel_info=accel_info) File "/usr/lib/python3/dist-packages/nova/virt/libvirt/driver.py", line 3663, in spawn cleanup_instance_disks=created_disks) File "/usr/lib/python3/dist-packages/nova/virt/libvirt/driver.py", line 6552, in _create_domain_and_network raise exception.VirtualInterfaceCreateException() nova.exception.VirtualInterfaceCreateException: Virtual Interface creation failed During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/usr/lib/python3/dist-packages/nova/compute/manager.py", line 2200, in _do_build_and_run_instance filter_properties, request_spec, accel_uuids) File "/usr/lib/python3/dist-packages/nova/compute/manager.py", line 2444, in _build_and_run_instance reason=msg) nova.exception.BuildAbortException: Build of instance 2a86a84b-50fc-415c-a15c-cb87398f37ea aborted: Failed to allocate the network(s), not rescheduling. *Created *Dec. 29, 2020, 9:18 a.m. *After this I can't ping the computer from the provider network interface.* I reinstalled openstack so many times and also I tried the train and victoria version and have the same problem. I attached log files of nova compute and neutron linux bridge from compute node and neutron server from controller node. thanks.