I bought a cheap NAS for file server at the office a few months ago. Didn't pay attention and found it only has 500 MB system memory and can't handle 3 concurrent users
So I bought a new TS-453A with 8GB of system memory. I think it should be sufficient lol. And the TS-231 is not a total loss - we already use one as offsite backup, so this one will be a redundant backup in a second offsite location