As I am not an expert in this kind of things, and after trying everything (open ports, static ip, etc.), I´ve done a soft factory restore “system only”, and I have:
“Port forwarding connection established” !!
The device is working well now and all the data is still there.
The machine did let me delete shares that I´ve created before and that i was not able to eliminate.
It seems the device needed some “cleaning” after all the wrong things I´m sure I´ve done since I bought it.
Now it seems running healthier. Hope keeps like that a long time.
Than you again, and congratulations for the forum.