Are you saying you verified your network health and speed with a tool such as iPerf?
You gave very little information on what steps you have taken or how you are coming to your conclusion of slow SMB speeds. Provide as much details as you can. If it is related to some SMB settings, I have found @awalkerix to be knowledgeable and helpful on the forums.
iX Systems has to be able to reproduce the problems on their end. I think most of the slow SMB has been network issues and non standard SMB settings.