The article explores the legitimacy of local 5G and upcoming 6G mobile communication networks in Europe. The paper paves the way for a new perspective for understanding the legitimacy of local 5G/6G mobile communication networks by applying the business model-based ecosystem perspective and legitimacy as a theoretical foundation. As regulations are expanding to consider the novel deployment model of local 5G and 6G mobile communication networks, the legitimacy of such networks is under-explored. Analyzing the regulatory approaches taken by two national regulatory authorities (NRA) in Europe, Finland and the UK, we identify seven legitimacy-related themes including innovation orientation, awareness and knowledge of how to build and design local networks, European harmonized spectrum management, competition, cybersecurity and risk assessment and equipment availability. Our study lays the groundwork for exploring how the application of the business model-based ecosystem perspective can be utilized to advance regulatory initiatives for local mobile communication network businesses. It also identifies which legitimacy-related aspects are involved in setting regulatory priorities.