A ton of issues with my 4tb My Cloud Drive

My drive started disappearing more and more from Windows until a few days ago, when I couldn’t log in to the shares anymore. I finally decided to do a full system restore. However, once that was done, it only reports 1.3tb of space. Not sure what is going on, any way to fix this? Is the drive malfunctioning?

What type of router do you have and how old is it? Is it 802.11ac and Gigabit?

Have you rebooted it since the system restore to see if the space would change?
Have you rebooted your router?

What OS do you have, is it Windows 10 with all updates?

It’s an RT-AC68U. I’ve rebooted multiple times, both the router and the drive. I’ve run a full diagnostic and I get an error, but not sure where it saves the log. I’ve requested to send report to support when I do it, but nothing seems to have happened when I press the button.