My My Could EX4 will not sync to My Book using NAS to USB sync. I get a fail notification and check system settings message.
You’ll probably have better luck in the dedicated subforum for the EX4 where users more familiar with that device may be able to assist. This subforum (My Cloud) is generally for the single bay device which is different than the EX4.
https://community.wd.com/c/network-attached-storage/wd-my-cloud-ex4
