I had the problem whereby my Windows 11 laptop couldn't access the files within my NAS drive. My old Windows 10 laptop and my Windows 11 desktop had no problem. I tried various things recommended in online articles, all to no avail. Eventually I gave up and had to accept that accessing files on my NAS drive had to be via my desktop or old laptop.
Then I had a different problem with my Windows 11 laptop, in that a blue screen appeared when it was switched on and I had to go through various steps such as selecting a language and keyboard type. Unfortunately, I ended up in a loop on subsequent screens that I couldn't get out of. So, as the laptop was still in warranty, I contacted the manufacturer, and the result of that was the laptop was returned for repair.
The subsequent listed repairs were,
operating system reinstalled
mother board replaced
DC in cable replaced.
The laptop has worked properly since its return and........
I can now access the files on my NAS drive from it!
I presume something relating to the reinstallation of the operating system has cured the NAS access problem.