This paper presents the experimental validation of a framework for the coordinated dispatch and control of multiple active distribution networks (ADNs) hosting distributed energy resource (DER). We show that the presented method, based on the alternating direction method of multipliers (ADMM), effectively allows to control multiple ADNs in a distributed way to ensure they achieve a common objective without revealing information on their DERs capabilities or grid model. This experimental validation is carried out using demonstrators at the DESL of EPFL and the NEST site at Empa, both in Switzerland. The coordination of the systems to share the flexibility of their controllable assets is demonstrated through a set of 24h experiments. Finally, the limitations of the method are discussed and future extensions proposed.