How to fix dead VLAN (4095) on neutron

If VMs on a newly created OpenStack network cannot ping the gateway or router, check the VLAN tags in openvswitch on the compute and network nodes with this command.

ovs-vsctl show

If the result shows tag: 4095, for example:

Port "qr-5c55955c-59"
tag: 4095
Interface "qr-5c55955c-59"
type: internal

or

Port "tapec669c5e-e1"
tag: 4095
Interface "tapec669c5e-e1"

the network interface has been assigned to a dead VLAN and cannot communicate with anything. Suggested fix Delete and recreate the network.