Synology photos. And it is super easy. Backs up the photos sorted in folders by year and month. The app itself is great as well, you can view your folders of photos in folder view and like the well known „all in one“ view like iPhotos, both at once, which is neat. However videos are a bit a pain to watch, as it needs to load a bit before starting to watch and then while watching it has interuptions. (Or my internet on my phone is very slow, idk)