iOS WD My Cloud app - Authentication Revoked

Your problem is common with most ALL My Cloud devices. I have fixed it many times on my device. The very short answer is your NAS and router need to connect again, so here is a quick fix for now – do NOT reboot your router now,but DO REBOOT YOUR My Cloud and after reboot the NAS and router will be in sync.

The details of this are in this link I replied to yesterday!