Next-generation computer networks are increasingly complex due to their size, heterogeneity, and dynamism, making them vulnerable to sophisticated, multi-stage and multi-vector attacks. Manual security reconfiguration methods are too slow and error-prone, leading to delays and misconfigurations. To address these problems, the recent literature on network security configuration has focused on automated reconfiguration approaches for faster and more resilient responses. However, the dynamic nature of modern computer networks impacts the preservation of security during the updates, as improper sequencing can create insecure transient states. In lights of these motivations, the FATO methodology has been proposed. The aim is to optimize the scheduling of configuration changes in distributed virtual firewalls to maximize the number of secure intermediate states, minimizing violations of prioritized security policies.