TimoThePig  ZCNE Certified

If you are able to access the login screen but your password is no longer accepted and you get only 'login failed'-message then the most likely reason is that your password contains some special characters that were allowed in the previous firmware versions but not any more in the current one, like exclamation mark. To get…

I had a similar problem between two NAS542 devices and I was able to solve it simply by changing the admin password so that it does not contain the exclamation mark ! as I had originally and as you also seem to have in your example above.