Web access problem - unable to create access account

Having created an access email for my parents I wanted to re-assign priviledges from administartor so deleted their access on web ui to create a new one with limited access now all I get is.

31602 - The web access account you requested for could not be created. Ensure that you do not have any network connectivity issues and try again.

UI shows that web access is connected with portforwarding set up and I can access the drive from web.

ideas please?

Is this happening for the particular account you want, or does this happen with any account? What if you turn off remote access and reboot your NAS to allow it to refresh?