The small Byzantine church of Agios Ioannis is located just southwest of the capital Skyros Chora and can be reached via the exit from the town to the Agios Dimitrios monastery. This road is indicated with a sign. On the route to the church and the monastery you will encounter a beautiful view of Skyros City and the sea. A moment to stop and take a look or take a photo. You end up at a (new) artificial water reservoir that is surrounded by an unpaved road. Nearby is the small Byzantine Agios Ioannis church with inside well-preserved frescoes of Jesus and the Virgin Mary with child. We were here in 2018 and visited this church with a guide. The door was open.
Below there is a map that should make it easier to find this small but pretty church.