Wdmycloud ex4 drive failed

Hello, it just happened to me that my wd my cloud ex4 have messages: drive failed in bay 1, 2, 3, and 4. I have all bays with 4 TB WD red each, and if i am not mistaken using RAID 5.
since i store all my personal documents there, i really appreciate if anyone could give any suggestion. thanks.

Can you still access your files? If yes then do a backup of those files to another storage. Contact WD support for drive replace if they are under warranty. It is strange to have all 4 drive go out at the same time. You might notice there should be red LED blinking on the front of the EX4.