Hi maconceicao, welcome to the WD Community. This normal, this is a message from the My Cloud desktop app, every time you want to do remote access. You can click on yes.
So, As a proud owner of a now EOL WDBA Series MyBook. I had to post what I just did.
New PC, needed the windows version of WDMyCloud.
Downloaded the install from the EOL page for the product and installed it.
Soon as it ran this issue popped up and it all flashed back to me as I have been really just using on network as a backup storage point, no need for the program.
So anyway, all the annoyance of this pop up came back and I was determined to resolve.
No matter what you do, when you trust the cert and let windows decide where to put it.
Windows, looks at it and goes, duh I told you its untrusted, so it puts it in the untrusted container.
Next time go ahead and add it to computer and choose not to let Windows do it and you follow the prompt and stick it in the “Trusted People” container.
Walla, message is gone for good.
What happens in 3 years when the cert actually expires? By then I will have a new WD NAS and this, if still working will be back to more mundane duties on my network.