updated machine to win 11 and lost shre files on rn204

Your screen dump cannot be seen by standard users (like me) until approved by a moderator, though it has now been approved. Tt's far more useful if you describe exactly what you did (there are multiple ways to map a drive) and what error massages or other results you saw than posting a single picture of the result.

That said, the first question I have is by "update to Windows 11" do you mean this is a new Windows 11 computer or that you updated Windows on your old computer to 11? Especially if it's a new computer, what else may be new (firewall/virus protection especially).  New user name and/or password?

Is the network designated as Private in Windows?

Exactly what version of OS6 is your NAS running?

So what process did you use to attempt the mapping?  Did you also try using the IP address instead of the NAS name?

You do not need SMB1 for Windows11. You should not be looking at any post related to legacy unit access to the NAS -- solutions for them are not appropriate to your OS6 NAS.

If this is the same computer you used with Win10, then we need to check if you are already connected to the NAS since Windows only allows one set of credentials to be used per device. To do that, pen a CMD prompt and enter the net use command. If the results show any connection, then you are probably trying to use different credentials from those already in use. You can enter net use * /delete and delete them, then try again with the mapping.