The max_routes parameter in neutron.conf can be increased to accommodate more routes per router.
# crudini --set /var/lib/config-data/puppet-generated/neutron/etc/neutron/neutron.conf DEFAULT max_routes 45
Restart the neutron_api service.
# podman restart neutron_api
This parameter must be set in neutron.conf after the service has been restarted, and then more than 30 routes can be added to a router.
# grep -i max_routes /var/lib/config-data/puppet-generated/neutron/etc/neutron/neutron.conf max_routes = 45
However, manually editing configuration changes are temporary. All configuration changes must be made through the Director for a permanent fix. Create a template wherein you set the desired value of max_routes parameter and pass this template as an environment file along with the rest of the templates in your deployment command.
[stack@undercloud-0 ~]$ cat increase_max_routes_per_router.yaml
parameter_defaults:
ControllerExtraConfig:
neutron::config::server_config:
DEFAULT/max_routes:
value: 45
The changes will take effect after a stack update.