Response from Federico:
Thanks again for everything and certainly I will use your tips to improve the apartment and improve the wifi issue. For many guests the option to have internet around the city and be able to connect with your smartphone everywhere has been a considerable plus, that's why the mobile router. In the apartment there is already a second wifi to get connected to 100% in case of problems (rarely successes for luck, and I always check the connection before the guests arrive) possibly the company has had problems, I don't yet know it. In any case, you're perfect guests and I hope you come back !