With the rise of organized cybercrime, information security has become one of the greatest challenges for modern organizations. Regardless of size or sector, every organization can potentially become a target of cyberattacks. This paper analyzes the fundamental guidelines for building a secure network infrastructure, including a review of various network architectures, key security protocols and measures, as well as systems for network monitoring and management. Special emphasis is placed on the regulatory framework, particularly the NIS2 directive, which demands stronger protection of information systems and networks that are crucial to society and the economy. Practical implementation guidelines for these measures are thoroughly discussed in the context of municipal networks. The paper also includes a case study of the City of Šibenik, which has been actively working on modernizing its network infrastructure and aligning with the requirements of the NIS2 directive, offering valuable insights into the challenges and solutions related to cybersecurity in local government.