Microsoft Developers recently decided that, via software upgrades, they would disable the SMB1 network parameter which also disables Netbios. The result is that when using file explorer you suddenly no longer have access to file management functions of your NAS drives as they disappear from the LAN (media player access is still possible).
I my case there was no error message as a source of information to start an investigation & Microsoft frontline support couldn’t (or wouldn’t) help. I was referred to the manufacturers of the NAS drives to “sort out” their software!
I had purchased a brand new mini PC to run Roon but couldn’t migrate files across via the network (my old PC, iMac & iPad were all working fine).
The link below, to Windows Support, describes the reasoning & most importantly how this affects different versions of Windows and how to reinstate SMB1 and Netbios.
So, if you can’t find your media storage on your network, click on the click as it could save you hours of frustration in various forums.
SMB1 not installed
Amazingly, a Microsoft support supervisor contacted me the following day and apologised for the inconvenience and advised my comments would be passed back to the developers.