No router submenu in your OpenStack Horizon dashboard, here is how to add it.
On your controller node go to
sudo vi /etc/openstack-dashboard/local_settings
Find OPENSTACK_NEUTRON_NETWORK = section
and set ‘enable_router’: False, to True,
Save the file and exit
sudo systemctl restart httpd
Refresh Horizon Dashboard
There it is!
Repeat same procedure for every network component you wish to see in OpenStack Horizon.