I am new to WD EX4, would learn how to have my IPhone X back up automatically to my WD MyCloud EX4?
Likely not going tp happen, One of the best ways to back up an iPhone is to use iTunes. About all you can back up with a WD NAS is the Camera Roll of an iOS device with the WD My CLoud app.
That is no good then, caused it cannot be replaced as a substitution for any cloud base storage. Unless there is an App to bridge the compatibility issues.