Mycloudex2ultra offline after a period of time

I have a problem with a new WDMYCLOUD EX2 ULTRA. I bought a discless case and install 2 HDD RED 4TB 256 Mb cache. The probles is: after a period of time the WD NAS is OFFLINE. Also via local network is not accesible. The only way to access again is to swotch off and ON again to restart the NAS. The LED og the unit are normally BLU. I removed the Stan-By option, I did an hard reset (40 sce push buttom), I reinstalled the new firmaware manually…Idon’t know what to do. Consider that I used a MyCloud single disk until april with the same router (ADB Crow AXVP4412 with EOLO custom Firmware. Help!!!

You may want to move your post to, or start a new post in, the correct My Cloud subforum where users more familiar with the EX2 Ultra may be able to assist with your question.

OS5 My Cloud EX Series
https://community.wd.com/c/os5/my-cloud-ex-series/255

This subforum (OS5 My Cloud) generally discusses a different My Cloud model; the second generation single bay/single drive My Cloud.

OK,
Thanks
Luca