Addendum:
After six months, the mobile phone is defective!
At the first contact with water, it was broken.
From because of IP58 which usually means water resistance, so it is indeed advertised.
Repair is no longer possible, Amazon has promised to send a new phone.
I have a Samsung S5 has IP57 and is really waterproof!
Will there but no longer try without extra water-tight enclosure.