This paper contains a comprehensive overview and analysis of the Internet of Things (IoT), including its basic concepts, technological foundations, and connection to the 5G network paradigm. The document explores in detail various aspects of the 5G network, including its technology, implementation strategy at the level of the European Union (EU) and the Republic of Croatia, as well as its impact on the global and European economy. The role of the 5G network in the context of the Internet of Things is also considered, as well as the application of artificial intelligence in this area. The second part of the paper deals with the legal aspects of IoT regulation, providing a detailed overview of the international legal framework and the EU's approach to the Internet of Things and artificial intelligence. This includes the EU's attitude towards artificial intelligence and the legal-regulatory framework of the Internet of Things within the EU. Possible directions of regulation and the recommended regulation ratio of the Internet of Things are also considered. The third part of the paper is devoted to the analysis of the electronic communications market in the context of new legislation and cyber security in the Republic of Croatia. This includes an overview of the electronic communications market, the role of IoT in that market, and the new legal-regulatory framework of electronic communications. The national legal-regulatory framework in the Republic of Croatia is also considered, including an analysis of the Act on Cybersecurity and the Act on Electronic Communications. Finally, the paper provides a comprehensive overview of cyber security in electronic communications, the most common types of cyber attacks, awareness of the risks of cyber attacks, and measures to protect against cyber attacks. It also explores privacy and data protection in the context of IoT, as well as the regulatory features of smart city services.