With the SMB3 Leasing Mode change introduced in Windows 10 build 16215 and Windows Server 2019, there is no longer a need to disable SMB2 and Oplocks.
If you are running Windows Server 2016 or earlier, you will still need to disable SMB2 and enable SMB1. Leasing Mode is set on the share only and it emulates SMB1 with Oplocks off. Since SMB1 is not being turned on it is more secure and won’t cause issues with other file shares.
Setting SMB3 Leasing Mode to none is done on the server via PowerShell with admin rights using the following command
Set-smbshare -name “(Name of the shared folder)” -LeasingMode none
If you use the get-smbconnection command on the client PC’s, it will still show the Dialect as 3.1.1(SMB3) this is correct.