Based on our experience with QKD devices, we analyze problems related to building and operating point-to-point long distance quantum communication. This includes transferring and detecting quantum signal over distances of 100 km, handling polarization noise in optical channels, feasible key generation rates, properties of quantum networks operating over long time intervals. We will build the necessary competences to be able to join with our quantum network to the European quantum internet project. We establish transnational quantum link and perform quantum key distribution, as well as build an intra-city quantum link in Budapest using optical fibres.