Why does NAS storage become unavailable and show invalid storage error?

The problem is due to the workgroup name that both the PC and Samba NAS have. The SMB protocol specifies there might be conflicts between Windows hosts and Samba shares. 

How to solve the issue

1. Login to the Server application via the Desktop client.
2. Navigate the server whose NAS is invalid.
3. Right-click on the server, and click Server settings.
4. Switch to Storage Management tab.
5. Remove the invalid NAS storage.
6. Re-Add the storage back, but INCLUDE workgroup information in the username field.

For example:
path : \\YOUR NAS IP\RECORDING FOLDER
username : YOUR NAS IP\NAS USERNAME
password : NAS PASSWORD