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,
'enable_router': True,
Save the file and exit
Restart Apache
sudo systemctl restart httpd
Refresh Horizon Dashboard
There it is!
Repeat same procedure for every network component you wish to see in OpenStack Horizon.