Why is my NAS326 unreachable from my tablet?

Almos

Hi, 
I have a new NAS326. I've configured it so I can read and write it from my PC, my mobile, but for my android tablet it's unreachable. The zcloud app can find it, but can't connect, in the browser I get only an IP unreachable error. How can I solve it? 

#NAS_Apr_2019