How to auto backup files over internet between WD Cloud EX4 and WD Cloud EX4

I have bought two WD Cloud EX4s. I would like to remote backup files from one WD Cloud EX4 (with Statics IP) to another WD Cloud EX4( dynastic IP). I have tried several ways (FTP) but failed.

Hello and welcome to the community,

Check page # 55 of the user’s manual for remote backup information.