The maximum number of host routes per subnet can't exceed 23.

Issue

To allow more than 20 static routes on a subnet, we have modified the neutron.conf file on each controller node and set the desired value, like 40

max_subnet_host_routes = 40

And restart the docker service neutron_api.

But the maximum number of host routes per subnet can't exceed 23. If we set 24 or more static routes the DHCP package doesn't bring the routes and the routing tables is populated only with the gateway.