This article gives you a clue, how you can access your NAS if that didn´t work in Windows 10.
Problem: „I am not able to access my NAS share from my Windows 10 computer anymore.”
Old NAS devices of the NSA series (from NSA220 up to NSA325v2) do only use SMBv1 for the network shares.
Microsoft has removed SMBv1 since Windows 10 Update 1709.
You can get more information here
Unfortunately, there won´t be new software updates for the NSA series. So there won´t be an upgrade to SMBv2 or SMBv3.
It might be possible to enable SMBv1 in Windows 10 again, but this would be completely on your own responsibility and we can´t provide support for non-Zyxel products:
Have a look: Microsoft SMBv1 enable or in our knowledge base
If this is not an option for you, you might consider an upgrade to a unit of the recent NAS series (NAS326, NAS520, NAS540, NAS542) which supports SMBv2.