After bug 24537, "we can use addresses in a variety of formats [in ILS-DI:AuthorizedIPs]. This includes 127.0.0.1, 192.168.1.0/24, 10.0.0, and so on." It would be nice if this was reflected in the description of the syspref. This syspref used to take a plain list of IPs, so if you missed it in the release notes, there is no hint that the functionality has been changed/enhanced.