No router submenu in your OpenStack Horizon dashboard, here is how to add it.
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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,
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Save the file and exit
Restart Apache
sudo systemctl restart httpd
Refresh Horizon Dashboard
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There it is!
Repeat same procedure for every network component you wish to see in OpenStack Horizon.