RN428 - Lost Volume, But Data Is There (64 TB)

So you've been unable to download the logs?  You've been unsuccessful in trying to boot with just the top two drives?

I think you misunderstood the point of StephenB's last post.  He is saying that the lack of a mounted volume always results in the inability to enable SSH, so that's not pointing to an issue with the OS partition, as I suggested it might.  Since there is no technical reason for that, it must just be something Netgear blocks (as they do when the password is still the default).  But it doesn't stop you from doing more troubleshooting, as nothing we've suggested requires SSH.