For using the login page on different IP Subnets, follow the procedure to set it for an IP/Subnet. I shall guide you the steps for setting for an assumed IP Subnet '172.16.248.0/22'.
1. Add a New template, set a suitable Template Id.
3. Select the 'Domain' of the access controller on which the IP series '172.16.248.0/22' is configured.
4. Put into 'Content' designed using the default login template.
5. Leave 'Set as Default Login Page' UNCHECKED.
6. Put the 172.16.248.0/22 in IP/CIDR
7. Save the Template.
8. Test the login page on one of the IP belonging to '172.16.248.0/22'.