Anyone else having problems accessing SMB shares on Monterey beta? Can not access Synology SAN shares, Windows Shares or Mac Shares since updating to 12.0 Beta (21A5248p).

Has anyone else been having problems with accessing Mac SMB shares with lots of subfolders from Windows 10 (Fast Track Developer Release) on Big Sur Beta 11.x. The problem appears to relate either to the number of folders/files in the share - it seems to occur with large shared folders only. I get a situation where the Mac server does not appear in Network in File Explorer on Windows, but I can connect to the server using \\servername in the File Explorer address bar and get an immediate connection and can browse contents of small shared folder trees. However, with large folder trees, after a few seconds the shares become inaccessible and I can no longer browse or access their contents. The same things happens if I create an explicit mapped drive connection using net.exe in command or powershell. I can see the server and shares using NET VIEW \\SERVERNAME and can map a drive using NET USE Drive: \\SERVERNAME\SHARENAME and the drive appears in File Explorer under This PC, but if I try to navigate to it, or to access it from a command prompt on the PC using the mapped drive letter, the command shell/File Explorer hang until there is a network timeout and no data is returned. After the Timeout the Command prompt returns: C:\Path The specified network name is no longer available. NET VIEW \\SERVERNAME still shows all shares on the server. NET VIEW does not show the server IPC connection After killing and reloading File Explorer all shares can still be seen under \\SERVERNAME. Attempting to browse one of them hangs File Explorer until timeout or kill/reload. While File Explorer is hung, NET VIEW \\SERVERNAME yields: System Error 53 The network path cannot be found I have tried changing the SMB share parameters in Settings on the Mac, but I have exhausted all combinations and it makes no difference too the behaviour. The PC and Mac are on the same WLAN in the same room. They exhibit the same behaviour if I connect them using a wired connection to a local switch. (No problem accessing Windows shares on the same PC from the same Mac and no problem accessing non-Mac SMB shares on other PCs or Synology NAS from the PC. Seems specific to access shares on Big Sur Beta 11.x from Windows 10. Worked okay on Big Sur Beta 10.x) Any ideas?