Cloud with has 520

hello everyone i need a little help, i would like to use my nas as a cloud of my small office. I created my folder inside the nas with all the data to be shared but from my mobile I can only see them when I am connected via wi-fi to the office network. When I am not using wi-fi, the cell application does not find the nas. Can you help me??? What settings need to be changed ???? Thanks everyone for the help.

Consumer Product Help Center