After reinstalling Windows 11 cannot connect to NAS from more than 1 account

This is very odd. A few days ago, I had to reinstall Windows 11 on my laptop. I downloaded the Media Creation Tool and performed a clean installation, a procedure I have execute hundreds of times. The installation required a Microsoft account, which I entered. After completing it and making my home network a private network, my Synology NAS turned up in Explorer.

However, for the first time in my life, after double clicking it, it said can't find it showing error code 0x80070035. It was accessible through a browser, but not in the network neighbourhood, not even entering \NAS (not the real name) in a command prompt. Only after creating a separate local account I was able to connect from there. So I made a network connection there using a drive letter, and could access all files. But only in that account! Returning to the other account and also a third, newly created account, the drive was no longer visible.

To be clear, I have done this many times and up until a couple of months ago this posed no problem whatsoever. What has changed? Should I reinstall Windows 11 from an earlier build? Is that even possible?

***Move from Windows / Windows 11 / Internet and connectivity***