I recently upgraded the drives in my QNAP TS-209. Everything appeared to go smoothly. I took the opportunity to upgrade to the latest firmware, which also completed successfully. I can connect to the admin panel just fine. So I'm 99.999% sure that the NAS is working fine.

The problem is I can't connect to it from Windows 7. I had it working before but can't remember how I set it up! (It was years ago)

I have installed the QNAP Finder program on two different machines, and it finds the NAS just fine.

Via Windows Explorer, this works:

\\NAS_NAME

...but this throws an error:

\\NAS_NAME\Public

I am sure the Public folder exists - I can see it in Explorer (and in the NAS admin panel, and if I SSH into the NAS I can browse to it). But I get an error saying "the network path is incorrect" or something like that (I've had a few variations with things like "check the spelling", etc.).

I strongly suspect that the problem is stale credentials on the clients. But I don't know how to fix it. Can anyone help?