Ananda
The Bunker Group
Seems the photos posted by @Sandhi Yudha is part of commencement of what TNI-AL call 'auxiliary submarine base' in Natuna.a bonus some nice photos of the KRI Ardadedali 404 arriving at Natuna. On the last photo we can see another Type 209/1400, but it is unclear if its the KRI Nagapasa 403 or the KRI Alugoro 405.
KSAL Resmikan Pembangunan Stasiun Bantu Kapal Selam di Natuna Halaman all - Kompas.com
Laksamana Yudo Margono menandatangani prasasti pembangunan stasiun bantu kapal selam dan peresmian Mes Tjiptadi, di Selat Lampa, Natuna. Halaman all
nasional.kompas.com
From Kompas artikel this base is not for longterm support for Submarine operations. However can be point for logistics and 'recharge' to prolong operation in the area.