[kolla-ansible]Network Problem after server reboot

Hello, after a restart of my cluster (and some problems...), I have one last problem with the VMs already present (before the restart). They all work fine….They all work, console access OK, network topology ok… But they can no longer communicate on the network, they do not obtain IP addresses by dhcp. Yet everything seems to be working. If I detach the interface, I create a new interface, it doesn't work. I cannot reach the routers. I cannot communicate with an instance on the same network. On the other hand, if I create a new instance, no problem, it works and can join the other instances and its router. Is there a way to fix this? The problem is where? in the database? Thank you in advance for your help. Franck VEDEL