Did you happen to try and create a share on your readNAS and get the following error:
Invalid name or illegal characters detected in name. Name is limited to alpha-numeric, underscore _, dash -, dollar sign $, and period characters, andmust start with an alpha character. Name cannot contain ''-snap'' and name cannot be used by an existing user account.
Turns out the reason is that some names are just "reserved"
from the post here:
it seems to be the case with "sys" and from personal experience its also the same with "mysql".
and:
says that "images" is also reserved.