8 hours ago
(Yesterday, 11:22 AM)admin Wrote: Is the computer in a domain? If the computer is in a domain, add the domain name before the user name and retry (domain\username).
No, it's not. But I tried this before posting here; you gave that hint already in the earlier dicussion mentioned above.
After switching "password protected sharing" off and on again on the target it works now - at least at the moment

As I learned earlier we had solutions that didn't survive a day or even a reboot.