Windows 11 Explorer - This folder is empty.

When I open Windows 11 Explorer and click on network drive U: I see this:

However, I know there are files on the drive, and if I expand drive U: in the navigation pane I see this:

To explain: the PC is plugged into a TP-Link C7 Archer Router, which also has a USB socket for a shared drive, and U: is mapped to this drive to enable sharing of media across computers on the network.

On Windows 10 Explorer the contents of this drive were always visible, similarly on Windows 7, although for Windows 10 to work I had to enable SMB 1.0/CIFS Sharing support. I also set this in Windows 11.

Once I have expanded drive U: in the navigation pane I can generally click again on U: and see the contents in the main window, but it is quite sporadic, and with some of the subfolders it seems impossible to get the contents to display, no matter how many times I click on them in the navigation pane. Is there some additional parameter I need to set in Windows 11 Explorer to ensure I can always see the contents of drive U:?

Possibly this may help you understand what's causing the problem.
One of the 4 subjects on that page is:
"Windows SMB v1 file sharing is broken in Windows 11 25H2".

Much more is to be found when searching the Internet with "windows 11 25h2 SMB1".

As I am not using SMB1 anymore (my NAS on my router does not need SMB1) I can't exactly tell what you should do to cure the problem.

@Kees
Many thanks for that information. Following your suggestion I found a link to this post

[Network Place (SMB)] How to Fix Windows 11 Not Working SMB Feature? | Official Support | ASUS Global

and I have tried implementing Method 1 and Method 2. It may require a reboot to check this, but it seems to have improved access.

Strange. I have the same setup with 25H2 26200.7171 and a Linksys router and I'm not seeing any issue at all. I only enabled SMB 1.0/CIFS Client on the Windows 11 machine. I'm using all default adapter settings (i.e. I have NOT disabled NetBIOS over TCP/IP).

This is due to changes to network authentication when using SMB 1.0. To return to the previous authentication that worked, open PowerShell as Administrator and execute:

Set-SmbClientConfiguration -RequireSecuritySignature $false
Set-SmbClientConfiguration -EnableInsecureGuestLogons $true